Sinn Fein's Westminster boycott and refusal to re-enter into Stormont power-sharing are to blame for the rise of dissident groups including the New IRA, the DUP's Jeffrey Donaldson claimed last night.
The MP lambasted the republican party for creating a "political vacuum" that has allowed the terrorists to thrive.
He hit out at Sinn Fein after it was revealed yesterday that the New IRA is now considered the biggest republican terror threat in Ireland since the Provisionals' 1994 ceasefire.
Mr Donaldson, whose cousins Sam and Alex Donaldson were killed by the IRA, said the DUP would now be asking PSNI Chief Constable George Hamilton for a fresh security assessment on the dissident threat level from the New IRA.
He added that the party was also prepared to ask Prime Minister Theresa May for more funds so the PSNI was "fully equipped to fight dissident groups".
Michael O'Sullivan, Assistant Garda Commissioner in charge of security, yesterday revealed the New IRA was more dangerous than any other dissident mob including Oglaigh na hEireann or the Continuity IRA.
Mr Donaldson said: "Sinn Fein's refusal to enter into a new power-sharing agreement at Stormont and their long standing policy of abstention from the UK Parliament has created a political vacuum that has allowed groups such as the New IRA to breathe and thrive.
"It's so disappointing that given the residual terrorist threat to Northern Ireland from extremists in the UK and the rest of the world, that Sinn Fein can't work within the existing democratic and political framework to show terrorists they have no place in today's world. They are not sending the message to dissident terrorists that they support the rule of law that will stop them winning."
In an exclusive interview with Belfast Telegraph sister paper the Irish Independent, Mr O'Sullivan said the rise in the New IRA was listed as 'severe' in Northern Ireland (the second highest level) while it is 'substantial' in Britain - meaning there is a strong possibility of an attack. He added: "This is the highest level since the Provisionals declared their ceasefire."
The New IRA is also believed to be more advanced in its capabilities to build explosive devices than any of its dissident counterparts, and has become skilled at counter-surveillance after its members trained in eastern Europe. It is said to have more than 50 activists listed as persons of interests to the Garda and intelligence services, with an army of more than 200 supporters willing to provide logistical support such as vehicles and safe houses.
In November 2012 it murdered prison officer David Black (52) on the M1 as he drove to work at Maghaberry. Last year prison warder Adrian Ismay (52) died after a being injured in a New IRA bomb detonated underneath his van in east Belfast.
Some of its members were also involved in the 2011 murder of PSNI constable Ronan Kerr and the earlier murders of off-duty British soldiers Mark Quinsey and Patrick Azimkar as they took delivery of a pizza outside Massereene barracks in Antrim.
Mr Donaldson added last night the DUP was supporting the Tories' counter-terrorism strategy as part of the £1bn deal to prop up Theresa May's administration. "We will be working closely with the Government to ensure the PSNI have the resources they need to fight these terrorists," he said.
Secretary of State James Brokenshire extended the June 29 deadline on power-sharing talks after the DUP and Sinn Fein reached a stalemate.