Politicians could be in for a pay raise but the government is shying away from responsibility because the decision is in the hands of an independent tribunal.

The independent Federal Remuneration Tribunal is undertaking a comprehensive review of politicians' pay.

It is expected to recommend MPs trade their current generous allowances for increases in base salaries.

Backbench salaries are tipped to almost double to $250,000.

And the pay packets of Prime Minister Julia Gillard, her ministers and also shadow ministers could be a whole lot fatter.

Ms Gillard, who now earns $366,366 annually, could get as much as $650,000 under any new system while Opposition Leader Tony Abbott's could go up from $260,000 to almost $480,000.

This contrasts with the pay increases currently being offered to federal public servants, which the Community and Public Sector Union has criticised as not keeping up with living costs.

Home Affairs Minister Brendan O'Connor said he was surprised by the news of potential pay raises.

"I didn't get into politics for the money and don't know too many people who did," he told ABC TV.

"Whatever the decision is I'll abide by it."

He said the tribunal was an independent body and had been legislated to ensure there was no political interference.

"I believe politicians should have no power over the assessment of their remuneration."

Mr O'Connor said had no problems with a past freeze on politicians salaries.

The Australian Greens have blasted the major parties on the pay issue, saying they both pushed through legislation that gave the tribunal free rein to set politicians' base pay.

Previously the tribunal could only make recommendations about pay, which the government could reject.

Senator Brown said the laws shed the politicians responsibility for pay increases.

The remuneration tribunal is expected to hand down its preliminary report by the end of the year.

MP salaries could almost double under new formula