Catholic bishops in Northern Ireland have expressed alarm at British government plans not to fund the investigation of the majority of around 2,000 unsolved killings from the Troubles.
The move will mean only a small number of killings will be fully investigated.
The bishops say the UK government has "moved away from the position of equal access to justice for all".
While the vast majority of the unsolved killings were carried out by paramilitary groups, the plan also applies to killings by the police and army.
Lawyers acting for the families of many of those killed by police officers or soldiers claim the move is designed to prevent investigations into those deaths.
The proposal means unsolved killings will be "swiftly" assessed by a newly established independent body.
Only those where there is "new compelling evidence and a realistic prospect of a prosecution" will move to a full investigation.
If it is deemed the criteria for a full inquiry is not, met families will be provided with as much information as possible and the investigation process will stop.
Once cases have been assessed there will be a legal bar on any future investigation.
The decision announced by Northern Ireland Secretary of State Brandon Lewis earlier this month has been criticised by the Irish government.
Tánaiste and Minister for Foreign Affairs Simon Coveney said it was a breach of the Stormont House Agreement reached by political leaders in Dublin, London and Northern Ireland in 2014.
The Catholic bishops in Northern Ireland have now also expressed concern.
In a letter to Brandon Lewis, they say that as a society Northern Ireland "must face up to the reality of the past" and "consider the actions of all involved".
They add: "State and non-state actors must be equally accountable before the law. Otherwise no authentic reconciliation can be achieved."
The letter says the Northern Ireland Catholic Council on Social Affairs cannot support any legislation that "provides that State-actors would not be equally subject to the rule of law". The letter says the bishops are concerned about the proposed requirements needed to pursue investigations.
"These are manifestly onerous and contrary to the normal procedure for the investigation and prosecution of crime," the letter says.
"We do not believe such approaches represent fair and open access to the pursuit of justice for all.
"In fact, these approaches would self-evidently discriminate against victims of Troubles-related crimes in Northern Ireland, and would therefore be a breach of Article 14 of the European Convention as provided by the first Schedule to the Human Rights Act 1998.
"With the information available to us at present, we disagree with this statement and do not believe it is consistent with the principles of the Stormont House Agreement or will deliver for all affected by the events of the past."