Senior UK military and political figures could end up in the dock as 400 victims denounce 'systemic' use of torture and cruelty.

A devastating 250-page dossier, detailing allegations of beatings, electrocution, mock executions and sexual assault, has been presented to the International Criminal Court, and could result in some of Britain's leading defence figures facing prosecution for "systematic" war crimes.

General Sir Peter Wall, the head of the British Army; former defence secretary Geoff Hoon; and former defence minister Adam Ingram are among those named in the report, entitled "The Responsibility of UK Officials for War Crimes Involving Systematic Detainee Abuse in Iraq from 2003-2008".

The damning dossier draws on cases of more than 400 Iraqis, representing "thousands of allegations of mistreatment amounting to war crimes of torture or cruel, inhuman or degrading treatment".

They range from "hooding" prisoners to burning, electric shocks, threats to kill and "cultural and religious humiliation". Other forms of alleged abuse include sexual assault, mock executions, threats of rape, death, and torture.

The formal complaint to the ICC, lodged yesterday, is the cumulation of several years' work by Public Interest Lawyers (PIL) and the European Centre for Constitutional and Human Rights (ECCHR). It calls for an investigation into the alleged war crimes, under Article 15 of the Rome Statute.

The dossier, seen by The Independent on Sunday, is the most detailed ever submitted to the ICC's Office of the Prosecutor on war crimes allegedly committed by British forces in Iraq. The court has already acknowledged that there was little doubt that war crimes were committed.

In 2006, it concluded: "There was a reasonable basis to believe that crimes within the jurisdiction of the court had been committed, namely wilful killing and inhuman treatment." At that time, prosecutors cited the low number of cases – fewer than 20 – as a reason for not mounting an investigation. But, since then, hundreds of other claims have come to light – prompting consideration of the complaint now. It is the start of a process which could result in British politicians and generals being put in the dock on war-crimes charges.

The sheer scale and seriousness of the allegations passes the "gravity" threshold to justify an investigation, according to the complaint. It continues "those who bear the greatest responsibility" for alleged war crimes "include individuals at the highest levels" of the British Army and political system. It concludes the evidence "justifies further investigation" into the criminal responsibility "of senior individuals within the UK military and government". It adds British military commanders "knew or should have known" that forces under their control "were committing or about to commit war crimes". And "civilian superiors knew or consciously disregarded information at their disposal, which clearly indicated that UK services personnel were committing war crimes in Iraq".

The complaint argues that "the pattern of abusive treatment by UK services personnel in Iraq continued over almost six years of military operations".

A number of top British officials face serious scrutiny, according to Phil Shiner of PIL. He said: "I think we easily meet the threshold for these issues to be looked at, I would be gobsmacked and bitterly disappointed if they don't look at this."

Only a handful of courts martial relating to the conduct of British forces in Iraq have been held to date. Just one has resulted in a conviction – Corporal Donald Payne was jailed for a year in 2007 for the inhuman treatment of Iraqi civilians. This one conviction aside, "Nobody has been found guilty of anything of any seriousness at all," said Mr Shiner.

The complaint being considered by the ICC presents evidence of the "systematic use of brutal violence, that at times resulted in the death of detainees, while in the custody of UK Services Personnel". And it claims "there is evidence of brutality combined with cruelty and forms of sadism, including sexual abuse, and sexual and religious humiliation". It points to the widespread use of "hooding", forcing people to remain in painful "stress positions", sleep deprivation, noise bombardment and deprivation of food and water. These interrogation techniques were used by British soldiers in Northern Ireland before being banned in 1972. There are "clear patterns" of the banned techniques being used "in a variety of different UK facilities [in Iraq] ... from 2003 to 2008," says the complaint. And evidence "suggests that failures to follow-up on or ensure accountability for ending such practices became a cause of further abuse. The obvious conclusion is that such mistreatment was systematic."

The report will be publicly released at the Law Society, London, on Tuesday. It comes as the ICC is under mounting pressure to demonstrate a willingness to act against war crimes committed by Western countries – and not solely focus on African nations. Last October, the ICC was criticised by the Ethiopian foreign minister, Tedros Adhanom, who accused it of being "a political instrument targeting Africa and Africans".

Professor William Schabas, a renowned expert on human rights law, based at Middlesex University, said: "What this application does is throw down the challenge to the court to show there are no double standards." He added: "There is definitely a case for an investigation by the ICC," and claimed "there's no doubt" that war crimes were perpetrated by British forces in Iraq. "People should be worried," he added.

The complaint amounts to "a prima facie investigation mapped out for the prosecutor", and is "supported by sophisticated legal argument which adheres to the requirements of the [ICC]," according to Professor Andrew Williams, a law expert at the University of Warwick and author of A Very British Killing: the Death of Baha Mousa.

In a statement, an MoD spokesperson said: "These matters are either under thorough investigation or have been dealt with ... further action through the ICC is unnecessary when the issues and allegations are already known to the UK Government, action is in hand and the UK courts have already issued judgments."

The spokesperson added: "We reject the suggestion the UK's Armed Forces – who operate in line with domestic and international law – have systematically tortured detainees."

Echoing this today, Foreign Secretary William Hague said there was no need for the ICC to investigate the allegations.

“These allegations are either under investigation already or have been dealt with already in a variety of ways, through the historic abuses system that has been established, through public inquiries, through the UK courts or the European courts,” Mr Hague told Sky News.

“There have been some cases of abuse that have been acknowledged and apologies and compensation have been paid appropriately. But the government has always been clear and the armed forces have been clear that they absolutely reject allegations of systematic abuses by the British armed forces.”

Wolfgang Kaleck, ECCHR secretary general, said: "With the current communication to the ICC we want to move forward the criminal prosecution against those political and military leaders in the UK who bear the most responsibility for systematic torture in Iraq." He added: "The International Criminal Court in The Hague is the last resort for victims of torture and mistreatment to achieve justice. Double standards in international criminal justice must end. War crimes and other severe violations of human rights must be investigated and prosecuted, regardless of whether they are committed by the most powerful."

General Sir Peter Wall, Geoff Hoon and Adam Ingram did not respond to requests for comment.

Allegations of torture

Testimonies of hundreds of Iraqis who say they were tortured by British soldiers are being considered by the International Criminal Court in The Hague. Here are a few of the accounts submitted (all names have been withheld).

man who was beaten in front of his family said: "They made me sit in a kneeling position with my head pushed downwards and then they started to beat me. They beat me on my face, back and stomach."

Another, who suffered more than 60 punches to his head, stated: "There were many soldiers pushing and throwing me... As each soldier caught me they would punch me." He described how his son was also abused: "A soldier brought my eight-year-old son into the room. The officer started slapping my son round his face and shouting at him... I was on the floor in a terrible condition and couldn't move."

Another man who was hooded stated: "Sand kept coming into the hood. It was extremely uncomfortable and difficult to breathe... We were left to kneel in the sun for hours. If I moved position and bent my head forward at all, a soldier would come and kick me hard."

A young detainee recalled: "The soldier put his boot on my chest and pulled my trousers down.... I was shouting and was curled up against the wall. Then the soldier pulled me by my legs away from the wall. He turned me over on my stomach. He started rubbing his penis on my back, while the other soldiers watched. Then I felt him ejaculate on my back. I was trying to move away but another soldier came and pressed his foot on my legs."

Another man said: "Interrogators spent a lot of time insulting my sister and other family members. They threatened to rape my sister and force me to watch and said they would also arrest my old mother and father."

And an individual held in solitary confinement said: "I was beaten regularly, and was not allowed to go to the toilet or to shower. The psychological suffering during this period is indescribable."

Rights violations

March 2003 US and British forces invade Iraq.

September Baha Mousa dies in British Army custody in Basra. Inquiry finds death was caused by factors including lack of food and water and stress positions used by British troops.

April 2004 US forces launch assault on the city of Fallujah. It later emerges napalm and depleted uranium were used in the attack. Human rights abuses, including the sexual abuse, rape and killing of prisoners by US forces at Abu Ghraib prison are made public.

May In aftermath of the Battle of Danny Boy in Basra, British troops allegedly abused the human rights of a number of Iraqi nationals – allegations being examined by the Al-Sweady inquiry. British troops deny they murdered any prisoners after they were captured.

September 2007 Seventeen Iraqi civilians killed and 20 injured in Baghdad by troops from the private security firm Blackwater Security Consulting.

Devastating Dossier On 'Abuse' By UK Forces In Iraq Goes To International Criminal Court