Northern Ireland's First Minister has warned he is prepared to collapse the Stormont Assembly if Sinn Fein does not honour the landmark agreement on policing and parades - but he also stressed he was confident republicans would deliver.

Peter Robinson said he was sure his partners in the power-sharing government were fully committed to the deal and did not expect to need the nuclear option.

"I think everybody has recognised there are methods available, particularly to the two main parties in this Assembly, which can be used at any time if they wish to bring down institutions," he told the assembly.

Elaborating on his cryptic reference last week to the "secret device" he had to ensure Sinn Fein compliance, Mr Robinson cited the example of former Ulster Unionist Party leader David Trimble, who triggered the suspension of the Assembly after resigning on the issue of IRA decommissioning.

"It's well recognised that just as the leader of the Ulster Unionist Party once wrote out his post-dated resignation and eventually caused a suspension of the Assembly, so too have I the ability to do exactly the same thing," he said.

But he added: "There has to be a time in any negotiating process when you look across the table and you make a determination whether you believe that that person is seriously going to keep the commitment that they are entering into."

The DUP and Sinn Fein agreement hammered out at the marathon summit at Hillsborough Castle, Co Down, set out procedures for the devolution of policing and justice powers as well as new structures to manage controversial Orange Order parades.

Deputy First Minister Mr McGuinness promised his party would honour the deal.

"It is much better to move forward in a positive vein than looking at the black side," he said.

"I travel with hope and optimism, I look on the bright side and whenever this party makes commitments, we are absolutely dedicated to keeping those commitments."