Divisions over policing and justice have effectively torpedoed the prospects of unionist unity, a senior UUP figure has claimed.

David McNarry said the DUP had ditched the chance for greater co-operation with his party by supporting Sinn Fein demand for the immediate transfer of law and order functions.

The Strangford representative's criticism of Peter Robinson's party came as the First Minister renewed his calls for unionists to work together ahead of the general election, telling his rivals his door is open to them.

Mr Robinson insisted the DUP and UUP has to join forces to recapture Westminster seats currently held by nationalists, such as South Belfast and Fermanagh and South Tyrone.

But Mr McNarry said the DUP's decision to sign up to the Hillsborough Agreement on justice devolution has effectively ended that possibility.

"Clearly the DUP have consummated their political marriage to Sinn Fein and in doing so ditched the prospect of unionist unity," he said. "But at what price? Freezing out fellow unionists, overloading the already malfunctioning Executive and turning it into a dysfunctional liability."

The Ulster Unionists were the only MLAs to oppose the Hillsborough deal at the crunch vote in the Assembly.

While they support transfer of justice powers in principle, they claim the Stormont Executive has not proved it can cope with the responsibility.

The party came under strong pressure from political opponents at the Assembly, the UK and Irish governments and current and past US administrations to support the agreement.

But they stood firm - a move that drew stinging rebukes from all sides of the chamber, with Mr Robinson particularly vociferous in his condemnation.