SINN Féin and the SDLP have demanded Theresa May retract her claim that only soldiers and police are facing Troubles investigations.
The prime minister's remarks, which are at odds with official figures, have drawn widespread criticism.
Downing Street was yesterday unable to offer any evidence to support the Tory leader's claim, with a spokesman only insisting that the current system for investigating offences committed during the conflict wasn't working.
Figures released by the PSNI last year show that cases involving British army personnel account for less than a third of its historical investigations.
Assistant Chief Constable Mark Hamilton, who heads up the PSNI’s legacy and justice department, said yesterday the figures had "not changed substantially" since then.
However, Mrs May told the House of Commons on Wednesday: "The situation we have at the moment is that the only people being investigated for these issues that happened in the past are those in our armed forces or those who served in law enforcement in Northern Ireland - that is patently unfair."
She added: "Terrorists are not being investigated, terrorists should be investigated and that is what the government wants to see."
Sinn Féin deputy leader Michelle O’Neill yesterday challenged Mrs May to withdraw what she described as her "misleading and mischievous" comments.
She said she had written to the Tory leader about her "patently inaccurate claims".
"These remarks are deeply insensitive to the loss and pain of hundreds of families who have been bereaved by the British state forces," the Mid Ulster MLA said.
"They have caused deep hurt and offence and could even undermine confidence in the rule of law and the administration of justice."
Ulster Unionist justice spokesman and former soldier Doug Beattie rejected claims that the British government was treating victims with contempt.
"Any interest Sinn Féin now have the victims of the Troubles has come almost 50 years too late to be of any use. They will not be allowed to re-write history," he said.
DUP MP Sir Jeffrey Donaldson also claimed Mrs May was "absolutely right" in her assertion.
"The vast majority of cases being examined relate to police and army," the Lagan Valley representative said.
However, SDLP leader Colum Eastwood also called on secretary of state Karen Bradley to "immediately correct the record".
The Foyle MLA said he "absolutely furious" at the British prime minister and the secretary of state, who nodded in agreement as Mrs May made her comments in Westminster.
"I have explained to Karen Bradley that her actions and that of the British government are harmful and hurtful to victims and survivors," he said.
"Without immediate action, it will be difficult for the British government to rebuild confidence surrounding their role in dealing with the past."
Former justice minister David Ford said the prime minister had "come close to political interference".
"That (Mrs May's intervention) is completely unhelpful and in fact dishonours the memory of the vast numbers who served in uniform and did their duty honestly, properly and at personal risk by defending those who broke the law," the Alliance MLA said.
Shadow Secretary of State Tony Lloyd also said the Conservative leader "may come to regret her words".
He said they were "unfair to the investigating officers of the PSNI, the prosecution authority and the courts".
"The reality is that the majority of cases going through these processes involve paramilitaries, not members of the security forces," Mr Lloyd said.
A consultation on legacy legislation was circulated by the Northern Ireland Office to Stormont parties earlier this week.
A spokesman for the British government said the current legacy process is "flawed and isn’t working for anyone".
"Right now too many cases are not being investigated, including hundreds of murders by terrorists," he said.
"We want the Historical Investigations Unit set up so that all outstanding cases are completed in a fair, balanced and proportionate way. That is why we want to launch the consultation soon so that everyone can have their say on the best way to deal with the past."
