British troops sent to Ukraine as part of a planned peacekeeping force could face “vexatious” human rights prosecutions, Sir Keir Starmer has been warned.

The Prime Minister is facing calls to authorise a blanket exemption from the European Convention on Human Rights for soldiers sent to deter Russia.

It comes amid fears that Moscow could look to exploit Britain’s adherence to the ECHR to pursue soldiers through the courts and undermine military morale.

James Cartlidge, the shadow defence secretary, has written to ministers urging them to “maximise protection for our forces” against human rights claims.

In a letter to John Healey, the Defence Secretary, he wrote: “You will be aware that British troops who served in Iraq faced a large number of vexatious claims about their conduct.

“This has led to uncertainty among military personnel and veterans, who are naturally concerned about vexatious claims being made against them in a potential Ukrainian theatre of war.

“To maximise protection for our forces, I would urge you to consider derogating from the ECHR for the duration of Britain’s deployment in Ukraine.”