A United Nations body has condemned Ministry of Defence plans to grant military veterans amnesty from prosecution for historical offences.

The Geneva-based UN Committee Against Torture called on the UK government to “refrain from enacting legislation that would grant amnesty or pardon” to troops accused of ill-treatment.

This week the defence secretary, Penny Mordaunt, announced proposals to grant immunity for offences committed more than 10 years ago in Iraq, Afghanistan or anywhere else outside the UK.She also called for such legal protection to be extended to those who served in Northern Ireland during the Troubles – a plan that has been resisted by the Northern Ireland Office.

The UN committee urged the UK to “establish responsibility and ensure accountability for any torture and ill-treatment committed by UK personnel in Iraq from 2003 to 2009, specifically by establishing a single, independent, public inquiry to investigate allegations of such conduct.”

It added: “The [UK] should refrain from enacting legislation that would grant amnesty or pardon where torture is concerned. It should also ensure that all victims of such torture and ill-treatment obtain redress.”

The committee said it was concerned “by recent statements by high-level officials that they are contemplating measures to shield former public officials from liability”.

In relation to Northern Ireland, it said the government should “refrain from enacting amnesties or statutes of limitations for torture or ill-treatment, which the committee has found to be inconsistent with states parties’ obligations under the convention [against torture].”

Grainne Teggart, Amnesty International UK’s Northern Ireland campaigns manager, said: “We call on the UK government to ensure there are no barriers to justice for all victims of Northern Ireland’s conflict and make clear there will be no amnesty for human rights abuses, including those committed by security forces.”

A Ministry of Defence spokeswoman said: “We are not proposing an amnesty. Our package of measures, focused on overseas military operations, will help avoid service personnel and veterans being subject to legal proceedings many years after the events in question where there is no new evidence. Wrongdoing in the armed forces will always be investigated in line with our legal and international obligations.”

The UN committee also backed calls for an independent judge-led inquiry into renditions that involved “alleged acts of torture and other ill-treatment of detainees held overseas committed by, at the instigation of or with the consent or acquiescence of British officials”.

A coalition of human rights organisations including Liberty, Redress, Reprieve and Freedom from Torture said the UK had repeatedly broken its own deadlines for making an announcement on a torture inquiry.

“Despite promising parliament on 2 July 2018 that it would update the house within 60 days on whether or not it would call such an inquiry, these 60 days came and went and we are now at 320 days and counting,” the groups said.