The Peace Pledge Union has encouraged MPs to throw out the Overseas Operations Bill when it faces its final vote in the Commons this evening.

The bill, nicknamed the War Crimes Immunity Bill by the Peace Pledge Union, has been criticised for introducing a “presumption against prosecution” for UK armed forces personnel accused of war-related crimes overseas after five years have passed.

The PPU welcomed the news that Labour MPs are planning to vote against the bill. At the last vote in September, the Labour leadership instructed their MPs to abstain, although some of them joined with other opposition parties to vote against.

Conservative rebels are expected to join with Labour and other opposition parties in voting against the bill this evening, raising the possibility of a government defeat.

The bill was passed in the Commons in September before going to Committee Stage to be discussed further. If MPs pass the bill again today, it will then go the House of Lords.

As well as the “presumption against prosecution” of armed forces personnel after five years, the bill will also introduce a six-year limit on armed forces personnel taking legal action against the Ministry of Defence. Critics say that, despite ministers' rhetoric, the bill is about protecting the government and military establishment rather than rank-and-file military personnel or civilians.

There are expected to be attempts in the Commons today to amend the bill so that allegations of torture are not covered by the “presumption against prosecution”. The bill already states that allegations of sexual offences should not be subject to a “presumption against prosecution”.

But the PPU said that removing torture from the “presumption” would not be enough to make the bill acceptable.

They said that the overall effect of the bill would be to put the armed forces further beyond the reach of the law. The UK armed forces are already allowed to run their own criminal courts and police force.

The bill comes less than a year after investigations by the Sunday Times, Guardian and BBC Panorama uncovered fresh evidence of UK troops killing civilians in Iraq and Afghanistan.

The PPU said that the recent arrest of British soldier Ahmed Al-Babati, for peacefully protesting against the UK's role in the war in Yemen, is a reminder that the armed forces routinely abuse the human rights of their own members. They have offered to support Al-Babati's right to protest if he faces court-martial.