The Ulster Unionist leader, Mr David Trimble, is preparing to implement a phased strategy of sanctions against Sinn Fein in an attempt to force IRA decommissioning.
At a meeting on Saturday, Mr Trimble outlined to his 110member executive a series of penalties against Sinn Fein which will be implemented over coming weeks if the IRA does not put its weapons beyond use.
Sources said the measures include a continuation of the ban on Sinn Fein attending North-South Ministerial Council meetings, and a ban on the party taking part in conferences involving both governments and the UK devolved administrations.
There will also be a move in the Assembly to exclude the North's Education Minister, Mr Martin McGuinness, and Health Minister, Ms Bairbre de Brun, from office if the other sanctions fail.
Mr Trimble's 3-1/2-hour meeting with his party executive - which includes MPs, Assembly members and councillors - was described as "frank".
It is understood he was urged to toughen his stance towards Sinn Fein by three anti-agreement MPs, Mr Jeffrey Donaldson, Mr Willie Thompson and the Rev Martin Smyth.
The UUP leader emerged from the discussions threatening to step up his sanctions against Sinn Fein.
"The party has endorsed our proposal, our intention over the course of coming weeks and months to continue that pressure, to sustain that pressure in whatever ways are available to us and indeed, where appropriate, to increase that pressure, which we intend to do," he said.
"Let there be no mistake about it, we are determined to achieve both devolution and decommissioning," Mr Trimble said.
He wanted to see republicans assume the same responsibility as his party had shown throughout the peace process, instead of simply taking all the advantages.
Mr Donaldson said: "It is clear these sanctions will be applied within a time-scale leading to the exclusion from office of Sinn Fein ministers in the event of the IRA failing to decommission."
However, the Sinn Fein president, Mr Gerry Adams, who briefed his ardcomhairle in Dublin on the current political talks, accused Mr Trimble of undermining the process.
"The way he is proceeding is counterproductive. It is offensive. He is supposed to be promoting the agreement," he said.
The DUP also criticised Mr Trimble's plans. The party's deputy leader, Mr Peter Robinson, described the sanctions as a ploy before the approaching Westminster elections.
"The pattern will be the increase of meaningless sanctions against Sinn Fein in the run-up to the elections and throwing concessions to them after the election is over," he said.
The North's Deputy First Minister, Mr Seamus Mallon, warned Mr Trimble he would not collude in the strategy against Sinn Fein.
Speaking on BBC Radio Ulster's Inside Politics, he said the UUP leader's approach was damaging the political negotiations.
"The political process with the pro-agreement parties now has come to the stage, I think the most base stage, where one beats other parties around the head actually to please the more vociferous members of one's own party.
"I think that is bad politics. I think it's bad for the party that is doing it. Certainly it is bad for the political process within which it is operating."