The government should scrap the "on-the-run" legislation and not agree to any Sinn Fein proposed changes, the Ulster Unionist Party has said.
Sir Reg Empey said he did not want "any more meddling"
Sinn Fein wants the bill scrapped after saying that allowing anyone involved in Troubles-related crime to avoid prison was not what they had agreed.
But UUP leader Sir Reg Empey said he did not want "any more meddling".
The Northern Ireland Office has said there is no other vehicle for dealing with the "on-the-run" issue.
On Tuesday, Sinn Fein vice-president Pat Doherty said the legislation was "far removed" from what had been agreed during 2001 talks with the government at Weston Park.
He also accused the government of "sleight of hand" in that the law would grant amnesty to security forces who committed murder during the Troubles.
However, a Northern Ireland Office spokesman said Sinn Fein were "deluding themselves", if they thought that there was an alternative to the bill.
Mr Doherty met Northern Ireland Secretary Peter Hain at Stormont on Tuesday and urged him to withdraw the legislation.
"We are now calling for it (the legislation) to be rejected and we are withdrawing from anything to do with it," he said.
Mr Doherty said Sinn Fein would also be advising republicans "on the run" not to seek registration under the legislation should it go through.
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.
Sinn Fein met Northern Ireland Secretary Peter Hain
Mr Doherty led a delegation of party members and victims' groups to meet Mr Hain on Tuesday to give their views on the Northern Ireland (Offences) Bill which is currently going through Parliament.
Sinn Fein initially welcomed it, but now realise it will not only give an amnesty to IRA members but also to any soldiers or police officers who committed murder during 30 years of violence.
DUP deputy leader Peter Robinson said there was
now no reason for the government to proceed with the "obnoxious and obscene" bill.
"Democratic representatives from Northern Ireland who sat on the committee scrutinising the on-the-run bill have been completely united in their opposition
to this judicial farce," he said.
"Now is the time to scrap this sickening legislation and for the government to make sure it never again gets into such a mess," he said.
Sir Reg said: "The legislation should indeed be scrapped, but government must not enter into any future negotiation with republicans that will result in even worse legislation.
"This distasteful side-deal which should never have seen the light of day in the first place must now be consigned to the dustbin where it belongs, never to be resurrected."
Conservative NI spokesman David Liddington said he believed the government was "stuck" with the bill.
"I hope they will think again. They have given some indications that they are prepared to look at amendments to this bill as it continues through Parliament," he told BBC News on Wednesday.
The Police Federation for Northern Ireland urged the prime minister to "take Sinn Fein at its word" and withdraw the legislation.
Federation Chairman Irwin Montgomery said: "Now is the opportunity to do the right thing - even if it is for the wrong reason of Sinn Fein hypocrisy in not wanting the legislation to apply to military or police personnel.
"Withdrawing the legislation will also preserve the integrity of the historic case review process. I urge this government to do the decent thing and abandon the bill."
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.