Crucial talks aimed at resolving the crisis at Stormont over IRA activity have been called for next week by both the British and Irish prime ministers.
David Cameron warned that the power-sharing arrangements and devolved institutions are under threat of collapse unless urgent action is taken.
In a statement, Downing Street said: “There is a clear need to convene urgent, intensive and focused cross-party talks, involving the parties engaged in the negotiations that led to the Stormont House Agreement.
“It is vital for the sustainability of the devolved institutions that all parties seize the opportunity for urgent talks to address these issues.”
The talks plan follows confirmation from security chiefs they would support an independent assessment of paramilitary groups.
Taoiseach Enda Kenny said: “We envisage that this process of talks should be short, focused and intensive and deal with full implementation of the Stormont House Agreement as well as the trust and confidence issues arising from the legacy of paramilitarism.
“If the sustainability of the devolved institutions is to be ensured, it is absolutely critical that these talks are advanced with a sense of urgency and that all of the parties constructively seize this opportunity.”
Mr Kenny and Mr Cameron spoke on the phone on Wednesday and agreed the initiative.
The talks are planned for Stormont House with Secretary of State Theresa Villiers representing London and Foreign Affairs Minister Charlie Flanagan, Dublin.
“The purpose of the talks is to secure full implementation of the Agreement and to deal with issues arising from the impact of continued paramilitary activity,” Downing Street said.
Both the Irish Government and the DUP support a new form of paramilitary monitoring of the ceasefires. The breakdown in relations at Stormont reached a new low after the killing of a former IRA commander Kevin McGuigan, allegedly by former terror associates, last month.
Theresa Villiers said the fallout from recent murders highlighted the need to see all paramilitary organisations disband.
Northern Ireland Secretary Theresa Villiers said the fallout from recent murders in Belfast highlighted the need to see all paramilitary organisations disband.
“The Prime Minister and I, along with the Irish Government, agree that there is a need for urgent, focused and intensive talks.
“A failure to resolve the issues under discussion would raise serious questions about the sustainability of the devolved institutions,” she said.
Ms Villiers added: “I would expect each of the parties to give these talks their highest priority as we seek to find a way forward – to implement in full the Stormont House Agreement and to look at ways of dealing with the scourge of paramilitarism, from wherever it might come.”
Justice Minister David Ford said: “No longer can this be allowed to continue. Uncertainty must be brought to an end and paramilitarism cannot remain in our society, poisoning relationships and being the great unsaid truth in Northern Ireland.
“These talks need to be a genuine attempt to move beyond the seemingly endless cycle of crisis after crisis, which is damaging the delivery of government and eroding public confidence in the political institutions.”