Penny Mordaunt, the defence secretary, has said she wanted soldiers who served during the Troubles in Northern Ireland to be covered by proposals to introduce an effective amnesty from prosecutions for all other military veterans.

The minister said she wanted to implement “a wider solution for the veterans’ community”, despite the fact the Northern Ireland secretary, Karen Bradley, has repeatedly ruled out amnesties to placate the region’s nationalist community.

Early on Wednesday, Mordaunt announced “a statutory presumption against prosecution” for alleged offences committed in the course of duty more than 10 years ago covering wars in Iraq and Afghanistan, but not Northern Ireland.

But following that announcement, Mordaunt later went further when asked whether she would like to see the proposed exemption extended to cover the period of the Troubles. “I do think it should cover Northern Ireland,” she said.

“We have failed to make progress,” the recently appointed minister added, on what she described “the lawfare issue” – a reference to a controversial idea that prosecutions of historic cases are used as a way of perpetuating a conflict by other means.

Pressure has been mounting in Conservative and military circles as the number of prosecutions of soldiers who served in Northern Ireland have increased. Last month a former paratrooper was prosecuted for the murder of two people at a civil rights march on Bloody Sunday in Derry in 1972.

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Until now, Northern Ireland has been dealt with separately. Ministers are due to conclude a consultation on so-called legacy issues, and have previously stated there should be no amnesty and the creation of a historical investigations unit.

Last month, a victims group Relatives for Justice, said that Bradley had promised them three times in a meeting that any future amnesty for soldiers will not apply to Northern Ireland.

But Downing Street declined to criticise Mordaunt’s intervention, suggesting that the presumption against prosecution could be extended to cover the Troubles. A spokesperson for No 10 said the Northern Ireland Office was engaged in a separate process and that “the MoD have fed into the NIO process and they will continue to do so”.

Mordaunt also indicated she had already secured some concessions regarding Northern Ireland, citing “learnings” from the Iraq historical allegations team, which was disbanded after many of the allegations it reviewed turned out to be untrue.

But there were a string of complaints after Mordaunt’s announcements. Human rights groups said existing protections in law should be sufficient to prevent vexatious prosecutions.

Sam Grant, a policy and campaigns manager at Liberty said: “All alleged serious criminal offences committed by forces personnel need to be criminally investigated and should not be time-barred. If the claims are not well founded, prosecutions will not follow.”

Mordaunt comments came after a speech at the Royal United Services Institute, a defence think tank. Several MPs from the party’s right were present, including Mark Francois, a prominent Brexiter and former armed forces minister, who congratulated her on the announcement.

“Will you promise that we didn’t abolish IHAT for Iraq to create IHAT2 for Northern Ireland, Francois asked. Mordaunt replied it was necessary to learn the lessons, arguing that “law firms interested in making a quick buck” had escalated their activities “not into the pursuit of justice but the pursuit of profit”.

Many of the Iraq cases were brought by campaigning human rights lawyer Phil Shiner, who was struck off as a lawyer on multiple grounds of professional misconduct, after it emerged that many of the claims he had brought turned out to be untrue.

Lord Dannatt, a former head of the armed forces, said if the government introduces a bill that excluded Northern Ireland from the 10-year “statutory presumption” against prosecution he would seek to amend it to reverse that exclusion.

Gavin Robinson, a DUP MP, complained that Mordaunt’s declaration was not inline with promises that had been made to him by Geoffrey Cox, the attorney general, at the end of January.

Speaking in the Commons, Robinson said: “I sought and received an assurance from the attorney general that any proposal brought forward to protect veterans would apply equally across the United Kingdom. In fact, he said it would be plainly wrong should it not apply.”

The DUP MP also asked why Mordaunt had not come to the Commons to announce the proposed policy. A written statement to parliament on the subject had been expected on Thursday.