Martin McGuinness, the former IRA chief-of-staff who is now deputy First Minister of Northern Ireland, is to run for the Irish presidency.

Sinn Féin will announce his bid to succeed fellow northerner Mary McAleese as head of state in the Irish Republic later tonight.

The Sinn Féin MP who admitted he was the Provisional IRA's second-in-command in Derry during Bloody Sunday will hold a press conference on Sunday explaining why he is standing for president.

But senior sources in Belfast were stressing that McGuinness' decision to stand in the presidential race south of the border would not destabilise the power-sharing executive back at Stormont.

McGuinness has built up a close personal relationship with Peter Robinson, the Democratic Unionist first minister in the five-party coalition in Northern Ireland.

Although McGuinness will have to step down temporarily from the post as deputy first minister during the three-week long presidential campaign sources said that would be "mess but not a crisis" for the power-sharing government in Belfast.

Whilst he is likely to increase Sinn Féin's national share of the vote in the Republic above the 9% it gained in this year's general election McGuinness is not expected to win the presidential contest.

In the intervening three weeks before polling day in the Republic McGuinness may well be temporarily replaced as deputy first minister by another Sinn Féin figure possibly the Newry and Armagh MP, and former IRA prisoner Conor Murphy.

The Derry-born former IRA commander's entry into the presidential election will inevitably raise questions about his past inside the Provisionals. The Guardian revealed earlier this week in documents it had obtained containing evidence from a former military intelligence officer Ian Hurst alleging that McGuinness was aware of the murder plot against two top police officers in 1989.

Hurt's testimony to the Smithwick Inquiry into alleged Garda-IRA collusion includes claims that British state agent Freddie Scappaticci was centrally involved in the plot and reported directly to McGuinness who was then on the IRA's council.

If McGuinness were to be elected as head of state it would mark a career during which he had been chief of staff of AN organisation outlawed in both Northern Ireland and the Republic and ends up being chief of staff of the officially recognised Irish Defence Forces.