Responsibility for law and order policy was transferred from London to Belfast at midnight, marking the end of 38 years of Whitehall control.

Democratic Unionist First Minister Peter Robinson said devolution of the functions was a real positive for the region.

"Monday should be a good day for Northern Ireland," he said.

"The Northern Ireland Assembly will take its place alongside the Scottish parliament in having policing and justice powers devolved."

Alliance party leader David Ford is widely expected to be selected as the new minister at a vote in Parliament Buildings, having already been identified as the preferred choice of the region's two main parties - Sinn Fein and Mr Robinson's DUP. But his likely appointment remains a bone of contention with the two minor partners in Stormont's four party coalition government.

The SDLP and Ulster Unionists believe they should have been considered for the post ahead of the cross-community Alliance Party, which doesn't have the electoral strength to take a seat at the Executive table by right.

Mr Ford emerged as the favourite after Sinn Fein and the DUP struck an agreement that they would not nominate from within their own ranks and the would-be minister had to command confidence of unionists and nationalists.

Ahead of the vote, UUP chief whip Fred Cobain reiterated his party's protest.

"We are facing another marker in Northern Ireland's political development - we can choose to continue on the path of carve-ups, gerrymandering and paralysis, or we can do the right thing," he said. This most important of portfolios must be appropriately allocated. It is not a 'gift' to bestow in exchange for political servitude."