The future of power-sharing in Northern Ireland hangs in the balance ahead of a crucial meeting of the Ulster Unionist Party's ruling council.

Saturday's meeting has been called by anti-Agreement unionists determined to force an end to power-sharing with republicans over alleged IRA ceasefire breaches.

As the battle for control of the party escalated, its leader, David Trimble, met anti-Agreement MP Jeffrey Donaldson on Friday in the interests of "avoiding confrontation".

Both men are attempting to persuade grassroots members to back their plans and have sent letters to the ruling council asking for their support.

David Trimble: Facing crucial council meeting

Mr Trimble said he wanted to speak to Mr Donaldson on the basis that Mr Donaldson's letter indicated a desire to preserve the assembly.

The two-hour meeting ended without agreement on a motion, but a party spokesman said contacts continued behind the scenes.

Afterwards, Mr Trimble said he understood why many unionists were concerned given the violence of recent times.

"This crisis is a result purely of the failure of republicans to deliver the promises that they have made," he told the BBC.

"Paramilitaries in general and the republicans, in particular, have not made sufficient progress towards the exclusively peaceful and democratic means that the Agreement sets out as the goal that should be achieved in this process.

"Republicans have been going slowly, if at all in that direction. That is the problem.

"The only one regret I have about Saturday's meeting is that it distracts attention from the failure of republicans and makes it look as if there are unionists who wish to destroy the progress that has already been made."

Mr Donaldson said he agreed that the crisis had been "created by republicans".

"That crisis has arisen out of the violence and the contradiction between Sinn Fein being in government and acting as ministers and lawmakers and on the streets orchestrating violence and acting as lawbreakers.

"We cannot continue with that contradiction."

However, he said he wanted to protect the institutions as devolution was "good for Northern Ireland".

Jeffrey Donaldson: Seeking grassroots support

In his letter to delegates, Mr Trimble said bringing down the power-sharing executive was not the answer.

Mr Trimble's letter argued that a violence monitor to be appointed by the government was a useful tool to keep pressure on republicans not to violate democratic principles.

However, in his letter, Mr Donaldson suggested the proposed violence monitor was no substitute for resolute action.

He promised to table a plan that would focus on the need to preserve the assembly while offering an effective mechanism to exclude Sinn Fein from power-sharing.

Saturday's special meeting is the ninth gathering of the 860-strong body called to challenge the policy of Mr Trimble, who has, so far, survived at every turn.

At the last ruling council meeting, he gained 56% of the vote following an IRA move on decommissioning.

But council votes have been close in the past and there is no guarantee of victory on Saturday.

The council meeting comes after some Ulster Unionists called for the party to withdraw from the Stormont executive because of reports alleging IRA activity in Northern Ireland and Colombia.

The council agreed to go into government with Sinn Fein two years ago, but it also has the power to pull Ulster Unionist ministers out.