A partial amnesty for police and soldiers’ actions during the Northern Ireland conflict would be difficult to administer, the country’s top prosecutor has said.
Sinn Fein and the Irish government have objected after some MPs called for a “statute of limitations” law.
Proposals on addressing the legacy of deaths and injuries during Northern Ireland’s 30 years of violence have not yet been published.
Departing Director of Public Prosecutions Barra McGrory QC said a partial safeguard from prosecution favouring the security forces would be legally questionable.
He said: “As DPP, a partial amnesty would be difficult to administer. It would certainly invite challenges but it is not for me to say whether it is legal or not.
“If it is a statute, it is a statute so it will have gone through parliament.
“In terms of the international legality of it, it would be questionable.”
MPs from the House of Commons Defence Committee have called for the blocking of prosecutions.
Veterans have argued that it was unfair to charge pensioners over crimes committed early in the conflict.
The government has said its preferred option for addressing the past is the 2014 Stormont House Agreement between the local parties, which did not include the proposal envisaged by some Conservative MPs.
Their opinions are well-known, including within government.
Stormont House included a range of measures to address the past, including an Historical Investigations Unit (HIU) to search for new opportunities to prosecute.
It also envisaged a Commission on Information Retrieval whereby relatives of the dead and injured could privately receive information about the deaths of their loved ones. Its information would be inadmissible for criminal legal proceedings.
Mr McGrory said around a quarter of his total workload was taken up with dealing with legacy issues.
He added: “The last 18 months the legal landscape from a prosecutorial perspective has become increasingly dominated by legacy, it is taking up a significant amount of time.”
He said as part of any implementation of the Stormont House Agreement resources would be made available to his successor to deal with the flow of cases referred by HIU investigators.
“That will very significantly increase the workload on the PPS as far as legacy is concerned.
“It would be utterly unsustainable under the current resource pot.
“I would expect that of the pot of money set aside to implement the Stormont House Agreement a significant amount of it would come our way but it will still nevertheless be a significant burden on the prosecutor’s office.”