Sinn Féin fully supports the peace process and believes any criminal act should be fully punished.

That is according to the deputy leader of the party Mary Lou McDonald, who has hit back at claims that the party is 'in denial' over the IRA.

The party has been under renewed pressure since it was claimed that some IRA members were responsible for the murder of Kevin McGuigan in Belfast.

Deputy McDonald says there is nowhere for the killers to hide, and that nobody can be in any doubt about Sinn Féin's position.

It comes as British Prime Minister David Cameron will hold a crisis meeting with Northern Ireland's first minister tomorrow.

It is because the Ulster Unionist Party (UUP) voted to withdraw from the power-sharing executive, after the PSNI claimed the Provisional IRA still exists.

Democratic Unionist Party (DUP) leader Peter Robinson will travel to Downing Street to try to find a solution.

Meranwhile, Mr Robinson has criticised the decision by the UUP to leave the Northern Ireland Executive.

Writing in the Belfast Telegraph, Mr Robinson says now is not the time to exit the battlefield.

The first minister says the political crisis calls for "cool heads, clear thinking and a steely resolve to ensure democracy and the rule of law triumph over terror and murder".

Meanwhile, Sinn Féin is also criticising the UUP, saying it is using the deaths of Kevin McGuigan and Gerard 'Jock' Davison as an excuse to leave the power sharing government.

Sinn Féin Laois-Offaly TD Brian Stanley says the UUP wanted to leave Stormont before the murders.