Longtime foes opened a final round of Northern Irish peace talks Monday with a sharp exchange of words and the shadow of violence clouding hopes of agreement.

Just an hour after the IRA's political wing, Sinn Fein, returned after an 18-day expulsion, the chief pro-British party revived old demands for guerrilla disarmament and opened the way for a possible new challenge to their rivals' presence at the negotiating table.Britain and Ireland want the talks to produce a peace package by April 9 that they could submit to referendums in both parts of Ireland in late May.

Sinn Fein was suspended from the talks after Britain and Ireland blamed the Irish Republican Army for two Northern Ireland murders.

Ulster Unionist Party leader David Trimble, implying IRA involvement in a rash of recent attacks that have been blamed on dissidents, called for a review of what had been achieved so far in the talks, including the failure to win a handover of guerrilla weapons.

Trimble quoted media reports linking IRA elements to several recent bombings and said a large bomb seized by Irish police in the border town of Dundalk Sunday was also "the work of leading IRA bombmakers."

Obliquely pointing a finger at both governments for readmitting Sinn Fein, he said: "We can't have a situation where people are turning a blind eye to violence and allowing people to participate in the talks on an entirely false basis."