Robinson avoided automatically triggering an election by naming Arlene Foster, the only minister from his Democratic Unionist Party (DUP) who did not step down on Thursday, as acting first minister.
“I am… standing aside as first minister and other DUP ministers will resign with immediate effect with the exception of Arlene Foster”, he said in a statement.
The DUP power-sharing deal with republican party Sinn Fein in Northern Ireland was a result of a 1998 peace agreement and helped bring an end to years of sectarian violence between Protestants and Catholics.
But questions remain over how long the power-sharing administration can continue after the walkout of Mr Robinson and three of the DUP’s four other ministers from the 13-member executive.
This move effectively collapses Stormont, the Northern Irish Assembly.
But a series of political dramas in Northern Ireland on September 10th-the most dramatic of which was the withdrawal from government of Peter Robinson, the first minister-has deepened a crisis that had been building in the province for weeks.
Mr Robinson had demanded the UK Government suspend the institutions outright to enable talks to be held.
The crisis was sparked by an ex-IRA man’s murder and a police assessment IRA members may have been involved.
Earlier on Thursday, a cross-party committee of the Northern Ireland Assembly voted against a DUP call for the assembly to be adjourned.
British Prime Minister David Cameron says he expects the parties to resume negotiations Monday in search of a settlement.
“Peter Robinson clearly can not make a decision as to whether he wants be in or out of the Executive”, he said.
A string of recent paramilitary-style attacks culminating in the McGuigan murder have prompted unionist parties, loyal to Britain, to accuse Sinn Fein of being dishonest about the IRA’s existence.
The Ulster Unionist party (UUP) said it would send a delegation to the discussions at Stormont, which aim to prevent the collapse of devolution and cross-community government.
“It is a sign of a complete breakdown in the working relationships within the Executive”.
Hamilton said he believed that “some of the Provisional IRA structure from the 1990s remains broadly in place” but its objective “has radically changed” and it was “not on a war footing”, adding that there was no evidence the killing was sanctioned by the organization.
Mr Martin McGuinness said he feared that elements opposed to the peace were involved in Mr McGuigan Sr’s murder, and the killing in May of former IRA commander Gerard “Jock” Davison.
This is despite the IRA officially announcing it had laid down its arms in 2005 – a key decision that made it easier for unionist politicians to share power with republican Sinn Féin.