The RUC Chief Constable, Mr Ronnie Flanagan, has blamed the Ulster Freedom Fighters (UFF) for three of the recent killings carried out by loyalists in the North.
The UFF, a cover name for the Ulster Defence Association, is supposed to be on ceasefire and is linked to the Ulster Democratic Party, which is in the Stormont talks.
"I have no doubt that some of the recent murders have been carried out by the UFF. I believe that on the basis of intelligence which I have to hand, and on the basis of strands of our investigation, including the analysis of a forensic nature in relation to certain of these incidences."
Mr Flanagan said he believed the UFF was responsible for the murders of Mr Eddie Treanor in north Belfast on New Year's Eve; of Mr Larry Brennan on the Ormeau Road in south Belfast on Monday night; and of Mr Ben Hughes in the Donegall Road area of Belfast on Wednesday night.
He added that an RUC team had been set up to co-ordinate the investigations into recent loyalist violence.
Meanwhile, in a statement yesterday, the Irish Republican Socialist Party, on behalf of the INLA, admitting killing Mr Jim Guiney on Monday.
The INLA said it would "not countenance the hypocrisy of loyalist paramilitaries to talk peace during the day and murder Catholics by night".
The escalating violence was discussed during a meeting of the cabinet in London yesterday, during which the Prime Minister, Mr Tony Blair, and the Northern Ireland Secretary, Dr Mo Mowlam, reiterated their determination to persevere with the talks.
The Prime Minister's official spokesman said Mr Blair and Dr Mowlam stressed the importance of ensuring that those who were attempting to derail the peace process would not be successful. "That's what they want, and what the democrats amongst us must prevent from happening," the spokesman said.
He said under the rules of the talks the participants could decide whether a party was abiding by the Mitchell Principles and make representations for its removal to the two governments. If that matter arose, the spokesman said, both governments would then consider the issue.
After a 45-minute meeting with Mr Blair at Downing Street, Lord Alderdice, the Alliance Party leader, stopped short of calling for the UDP's expulsion from the talks. However, he said the party faced a stark choice if it was to remain at the table.
He said the UDP had to split from the UFF and rely on the support of its voters or find itself outside the talks process "along with the violent men".
Pointing to next week's multiparty talks in London, he said they should not be dominated by the question of the UDP's involvement. Everyone had real work to do, and both governments must make a decision "about people who we do believe have breached the Mitchell Principles".
If a party did not adhere to the Mitchell Principles "they have no right to be in the talks".
Asked about the role of Sinn Fein in the talks following the IRA's rejection of the British-Irish propositions paper, Lord Alderdice said the party could find itself facing the same choice as the UDP. "That is, do they split from the IRA or do they stay with the IRA and in the long-run find themselves outside the talks?"
Mr Willie Thompson, of the Ulster Unionist Party, who has been opposed to his party's involvement in the talks, said Mr Flanagan's disclosure made the UDP's position untenable.
He said the UUP should work to have the UDP removed from the talks.
Mr David Adams, of the UDP, described the development as a major difficulty. He said his party was trying to bring the killings to an end and to get the peace process back on track.
"The logic of the Alliance Party's position, where they say that we have to cut all ties with loyalist paramilitaries in order to satisfy them and stay in the process, doesn't stand up to examination."
Earlier, the Ulster Unionist security spokesman, Mr Ken Maginnis, said there was enough evidence for the British government to remove one loyalist party from the talks, although he did not name the party, and to remove Sinn Fein.
In other political developments, the deputy leader of the Ulster Unionist Party, Mr John Taylor, reacted to the IRA statement describing the recent Heads of Agreement paper issued by the two governments as "a pro-unionist document" which had created a crisis in the peace process.
Mr Taylor said it was "clearly an attempt to intimidate both the Irish and UK governments to draw back from their jointlyagreed position".
He said that if either government weakened its support for the paper, his party would seriously review its continued participation in the talks.
The Sinn Fein president, Mr Gerry Adams, accused Mr Taylor of irresponsibility and hypocrisy and said his remarks were part of "a concerted campaign by all shades of unionism to impose a unionist agenda inside the negotiations process and outside it".
Mr Peter Robinson, deputy leader of the DUP, said Mr Taylor had walked the UUP into a trap in going into talks and was now trying to dig them "out of the mess".
An SDLP talks negotiator, Mr Sean Farren, said Sinn Fein claims that the Heads of Agreement paper was "exclusively unionist" were untrue. Sinn Fein had "failed to appreciate the delicate balance necessary for a successful outcome" to the talks.
The Conservative Northern Ireland spokesman, Mr Andrew Mackay, said last night the talks would collapse unless the British government expelled the UDP.
He said there could be no public confidence in the democratic process unless the Mitchell Principles were upheld.