Legislation dealing with "on-the-runs" is "just a cover-up process negotiated between the British government and Sinn Fein", the SDLP has claimed.
SDLP leader Mark Durkan is set to outline his party's concerns
SDLP leader Mark Durkan has outlined the party's concerns about proposed legislation allowing fugitives from Northern Ireland to return home.
He met NIO minister David Hanson to hand over a "detailed critique" of the bill, published last week.
The plans cover up to 150 people wanted for crimes committed before 1998.
They would have their cases heard by a special tribunal, and if found guilty would be freed on licence without having to go to jail.
Unionists and terrorist victims expressed their outrage at the law, calling it an effective amnesty.
The government and Sinn Fein argue that it clears up "an anomaly" left by the release of those already in jail after the 1998 Good Friday Agreement.
Mr Durkan said many countries had attempted a truth process, and although none has been perfect, "all have been better than this".
"Because there is no time limit on the legislation, those responsible for the 2,100 unsolved killings can sit back and wait to see if the police ever come knocking on their door," he said.
"If they do, then they can apply to be an on-the-run from the comfort of their own homes.
"Sinn Fein even negotiated with the British government that the killers don't have to turn up in court and listen to how they shattered victims' lives."
The leader of the Alliance Party, David Ford, is meeting Conservative and Liberal Democrat spokesmen on Northern Ireland, about the on-the-runs issue.
Alliance want amendments to the legislation that would mean fugitives had to appear in court for their hearing and for clarification on the status of those exiled by paramilitary groups.
The proposed law would set up a two-stage process. First someone who will be known as the certification officer will decide if someone is eligible for the scheme.
This could be a paramilitary on-the-run, someone living in Northern Ireland who is charged with an offence before 1998 or a member of the security forces accused of an offence committed when they were combating terrorism.
The case would then go to a special tribunal, consisting of a retired judge sitting without a jury. The tribunal would have all the normal powers of the Crown Court but accused would not have to appear for their trial.
If found guilty they would get a criminal record but would be freed on licence. They would have to provide fingerprints and DNA samples to be granted their licence.
The scheme will be temporary but a precise cut-off period is not specified in the bill - instead its expiry is linked to the lifetime of the chief constable's historic cases review team, which is looking at unsolved murders during the Troubles.
The measures are contained in the Northern Ireland Offences Bill which is expected to get a rough ride as it makes its way through parliament.