Nationalist politicians in Northern Ireland have described the decision to stop the prosecution of two former soldiers over three Troubles deaths as “devastating” for the victims’ families.

However, unionists have highlighted the difficulties for the justice system in bringing prosecutions for deaths from several decades ago.

The Public Prosecution Service has 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.

Deputy First Minister Michelle O’Neill of Sinn Fein said it was a “bad day for justice”.

“We will continue to stand by the Bloody Sunday and Hegarty families,” she tweeted.

SDLP leader and Foyle MP Colum Eastwood said the decision was “bitterly disappointing” and has raised concerns about the way families have been treated.

Mr Eastwood said: “This is devastating news.

“Devastating for the Bloody Sunday families and the family of Daniel Hegarty who have placed their faith in process after process only to be let down badly as they seek justice and accountability for the murder of their loved ones.

“It is galling that these cases appear to have collapsed because the British Army’s historical investigation process was so deficient that the evidence collected is considered to be inadmissible.

“These families are now in a position where their loved ones were killed by members of the British Army and their prosecutions have been discontinued because of the conduct of the British Army.

“It is totally unjust.”

DUP MP for East Londonderry, Gregory Campbell, said any prosecution should only be brought when there is evidence which is admissible in court proceedings.

He said: “It is entirely understandable that any family who have lost loved ones will continue to seek justice and find some closure.

“There are many thousands of families across Northern Ireland who are in that same position but in those cases they have not even had the benefit of any meaningful investigation into their loved one’s murder.

“I have repeatedly indicated that after 40 or 50 years it is going to be almost impossible to reconstruct accurately the context in which soldiers or police officers were operating at the time of terror.”

Ulster Unionist leader Doug Beattie said the passage of time since the deaths led to Friday’s decision.

He told the BBC: “We have to have trust in our justice system, this has got a long way to run.

“I do think that it is difficult to get evidence that will stand up in a court of law that will get any form of convictions this far on.

“The justice system has not worked and dealing with legacy has not worked and it is difficult to see how we are going to get out of where we are now.”

Conservative MP Johnny Mercer, who resigned as a defence minister over the treatment of veterans who served in Northern Ireland, said he had sympathy with the families, but said it was difficult to progress prosecutions after so many years.

He told the BBC: “I don’t think that you can have prosecutions of sufficient integrity that will stick 40/50 years later after these events and I feel very strongly that Government has failed veterans of that conflict.

“But it is not one-sided, I have a huge amount of sympathy for the families.”

Alliance MP Stephen Farry said his thoughts were with the families of victims.

He said: “While the PPS has concluded there was no reasonable prospect of the evidence in the cases being ruled as admissible, that will in no way ease the emotions being felt by those families and the wider community.”