A cross-community group representing victims and survivors of the Troubles has warned the Prime Minister it would be “fundamentally wrong” to grant an amnesty for all killings during the conflict.

The Wave Trauma centre has written an open letter to Boris Johnson following the recent collapse of high profile legacy cases.

The letter argues that dealing effectively with “complex and sensitive legacy issues” will not be done by “perverting the criminal justice system”.

Proposals briefed to the Times newspaper in May suggested that the Government is planning to end all prosecutions for suspected offences, whether carried out by veterans or by republican and loyalist paramilitaries.

“Those briefings have confirmed that the core motivation behind the policy is not to deal with complex legacy issues in a coherent and sensitive way, but rather to protect veterans from potential prosecution by a de facto amnesty that will include the very paramilitaries who murdered their colleagues as well as thousands of civilians,” the letter states.

“We simply cannot believe that veterans would want that to happen to the families of their fellow service men and women killed during the Troubles.

“If anyone in Downing Street or the Ministry of Defence or the Northern Ireland Office seriously thinks that an amnesty of this nature can form the foundation upon which reconciliation could be built then it shows how little they understand the nature of the pain and trauma which continues to be suffered by victims and survivors and their families.”

It emerged this week that the prosecution of two former soldiers for Troubles killings, including two on Bloody Sunday, are to be halted.

Northern Ireland’s Public Prosecution Service announced that the case against Soldier F for the murder of James Wray and William McKinney on Bloody Sunday in Londonderry in 1972 will not proceed.

The prosecution of another veteran, Soldier B, for the murder of 15-year-old Daniel Hegarty in Derry later in 1972, will also not proceed, the PPS said.

The open letter to the Prime Minister asks: “Would the families of the 7/7 bombings, or the Manchester bombing, or any other atrocity be asked to draw a line under their own grief and pursuit of justice?”

Among the signatories to the letter are Cathy McCann, chair of the Wave Trauma Centre, whose father was murdered by the B Specials auxiliary police in 1969, in a case that remains unresolved.

In 1990, Ms McCann was severely injured as the sole survivor in a roadside bomb in which a nun and three policemen were murdered by the Provisional IRA.

Other signatories include former Wave chair Damien McNally, whose father was murdered by loyalists in 1976 in a unresolved case, Rev Dr David Clements, whose father was an RUC officer murdered by the Provisional IRA in 1985 and Jean Caldwell, whose husband was murdered by the Provisional IRA in 1992.

The letter warns that an amnesty on conflict era killings “will not aid reconciliation” but will will exacerbate “the anguish and bitterness that will bleed into subsequent generations”.

It argues that the proposals would also bring comfort to those who “were still prepared to maim and kill” by sending a message that “if they hold on long enough they will not have to answer for what they have done”.

Shadow secretary of state for Northern Ireland Labour MP Louise Haigh called for clarity on the situation.

She said: “This Government gave victims their word – they would deliver the proper investigations denied to victims and their families for so long.

“Reports suggest they want to tear that pledge up, and with it cruelly deny families the chance of finding the truth about what happened to their loved ones.

“The vast majority of outstanding investigations relate to republican and loyalist terrorist attacks.

“The Prime Minister should look victims’ families in the eye, and explain why he wants to close the book on their cases.”

A UK government spokesperson said: “The Government is fully committed to engaging with Wave and other victims groups to deliver a way forward on legacy issues that focuses on information recovery and reconciliation, and ends the cycle of investigations.”