The new chief of the defence staff, Gen Sir Nick Carter, vowed to fight against sweeping moves to prosecute British soldiers over their role in Northern Ireland.

He said individual soldiers involved in wrongdoing could not expect immunity but he was opposed to veterans being pursued by people with “vexatious claims”. He added: “That will not happen on my watch. Absolutely not.”

Theresa May found herself at the centre of controversy earlier this year when she agreed to a consultation on the legacy of the Troubles that did not include, as some Conservative ministers and backbenchers are demanding, a statute of limitations. Such a statute would have protected British army veterans from prosecution. But both Sinn Féin and the Democratic Unionist party opposed the measure.

Carter, speaking to journalists at RAF Coningsby in Lincolnshire, praised the performance of the British army in Northern Ireland and warned of the danger such retrospective actions might have on army morale.

“It is right and proper that if our soldiers have done something wrong then they should clearly be investigated,” he said. “But only if they have done something wrong. We need to have standards, we need to have values that people are held against otherwise we will lose the moral high ground.”

He added: “What is fundamentally wrong though is if they’re chased by people who are making vexatious claims – and that will not happen on my watch. Absolutely not. If you end up with a clutch of vexatious claims then that undermines morale and has the risk of undermining our combat ethos and our fighting spirit. I would absolutely stamp on any of that sort of activity.”

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Carter was more robust than his predecessor Air Chief Marshal Sir Stuart Peach. He added: “What we must try and remind ourselves about this whole Northern Ireland issue is actually what an extraordinarily amazing task the British Army did through 30 years in Northern Ireland.

“And we wouldn’t be in a position which we now are in if the British army hadn’t done a remarkable job in getting us to that position – and I really hope that’s not forgotten in all of this.”

He said service personnel facing investigation would receive as much help as they needed. “The point I’d make is that we as an institution … are absolutely going to look after those people who are being investigated this way to the best of our ability.

“A lot of people have got a lot of opinions about that and that’s part of the consultation – and I think it would be wrong for me to prejudge which direction it went in. I think it is sad this is happening. I think that of course there is a process of consultation going on at the moment and I don’t really want to prejudge where that consultation goes.”