THE Irish government last night denied reports that it was blocking police plans to bring the Omagh bombers to justice.

Dublin Justice Minister John O'Donoghue said the allegations of political interference were ''completely without foundation''.

Twenty-nine people, including a woman heavily pregnant with twins, were killed when a car bomb planted by the Real IRA exploded in the Co Tyrone town two years ago.

The same organisation yesterday vowed to avenge the murder of one of its members in west Belfast three days ago.

The killing of Joseph O'Connor, 26, in Ballymurphy, west Belfast, also placed renewed pressure on Northern Ireland First Minister David Trimble to seek the expulsion of Sinn Fein ministers from the power-sharing Stormont regime amid claims that it was carried out by its armed wing, the Provisional IRA.

Mr O'Donoghue said: ''The allegation that the Irish government has allowed political considerations to interfere with the bringing to justice of those responsible for the atrocity at Omagh is completely without foundation.''

However, Victor Barker, whose son James, 12, was killed in the tragedy was unconvinced by the assurance. He said: ''I want the Irish government to look into it further to make sure we're not being fobbed off.''

The row is set to be raised in the Irish Parliament today by Ireland's main opposition party, Fine Gael.

Meanwhile, Northern Ireland's First Minister David Trimble warned that Ulster Unionists are prepared to take action if the IRA does not disarm.

Mr Trimble told a party meeting in Aughnacloy, Co Tyrone, that the IRA had to deliver on its promise in May to ''put its weapons completely and verifiably out of use''.

If it didn't, he told republicans: ''The Ulster Unionist Party will have to undertake a measured and proportionate response to match the republican movement's failure to honour promises it made in May.''

Mr Trimble, who faces a meeting of the 860 member Ulster Unionist Council on October 28 to review his party's participation in power sharing with Sinn Fein, accused republicans of procrastinating on disarmament.

Mr Trimble's warning that his party would respond if the IRA failed to disarm came after anti-Agreement unionists in the Northern Ireland Assembly urged him to seek Sinn Fein's expulsion.

Democratic Unionist Ian Paisley Jr claimed allegations that the IRA leadership sanctioned arms smuggling in Florida and Joseph O'Connor's murder were grounds for an exclusion motion.