Northern Ireland's parties are being called into talks next week to resolve the political deadlock in Stormont.

British Prime Minister David Cameron and Taoiseach Enda Kenny have announced crisis talks focusing “confidence issues arising from the legacy of paramilitarism” after allegations that the Provisional IRA (PIRA) still exists and has murdered ex-IRA man Kevin McGuigan in east Belfast last month.

The Ulster Unionist party (UUP) decided to leave powersharing because it said it could no longer work with Sinn Fein in the current environment, plunging Northern Ireland’s power-sharing into crisis, the Guardian reports.

A Downing Street spokesman said Cameron and Kenny discussed the crisis over the phone on Thursday.

“They agreed that the current situation in Northern Ireland is serious and, without urgent progress, there is a real threat to the stability of the devolved institutions.”

In a statement, Downing Street said: "As a result of these discussions the Government has concluded that 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 Guardian reports that all five parties in the regional government will be asked to attend the talks hosted by the two governments.

In a statement, 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."