Concern was expressed that nobody has been charged with the Omagh bombing of nearly two years ago.

The Fine Gael spokesman on justice, Mr Jim Higgins, asked: "Why is it that the additional powers willingly given by this House and the Seanad on September 2nd, 1998, have not been effective in bringing a single charge against anybody involved in the planning or the execution of the Omagh bomb?"

Describing the bombing as "an act of indescribable evil", the Labour spokesman on justice, Mr Brendan Howlin, said: "It is disappointing that no convictions have been secured, following the enactment of the legislation, but what is even more surprising is that there has not been a single prosecution taken, or conviction secured, under this legislation that we were told in September 1998 was so badly needed."

In a debate on a resolution renewing the Offences Against the State (Amendment) Act, 1998, Mr Higgins asked if the Minister for Justice, Mr O'Donoghue, agreed with the assessment of the Garda Commissioner that the likelihood was that those responsible for the Omagh atrocity would never be caught.

Mr Higgins said that the clear message intended to entice the House and the Seanad into embracing the legislation in 1998 was that the perpetrators of the Omagh bombing were known and the legislative tools were required to put them behind bars.

"To date there is nobody behind bars. If we know who they are, and where they are, why are they not behind bars?"

Mr Howlin said that the failure to use powers provided by the Oireachtas raised very legitimate questions as to whether the powers were needed, and whether, given their non-use, they should remain on the statute book.

While his party was supporting the renewal of the Act, it should not be taken that it would necessarily agree to any further extension, especially if its provisions continued to lie unused.

The Minister for Justice, Mr O'Donoghue, said that the Garda-RUC investigation into the Omagh bombing was still being "actively and vigorously" pursued.

Mr Des O'Malley (PD, Limerick East) said he was not at all satisfied that the organisation, which started life as the Provisional IRA, no longer constituted a threat to the State.

"Like the Garda, we would be very foolish indeed if we were to lower our guard in this respect and not retain the necessary powers to deal with subversion and terrorism."

Mr Caoimhghin O Caolain (SF, Cavan-Monaghan) deplored the renewal of "repressive legislation".

The Bill had been enacted "in the heat of justified anger at the Omagh bombing in which 29 people died," he said. "The Minister is asking us today to renew the provision whereby the exercise of the right to silence can be used to corroborate the word of the Garda.

"The exercise of the right to silence can mean that the court is empowered to draw inferences from failure to mention any fact later relied on by the defence. In effect, the right to silence is removed," he said.

Mr Joe Higgins (SP, Dublin West) said he was opposed to the renewal of the Act. The Omagh bombing was "an appalling atrocity", but the legislation applied to all people on the island.

"It can be used against people who are innocent, and it turns on the head many crucial aspects of law in this country," he said.

The Tanaiste said she shared the concern expressed about the threat to the UFF ceasefire.

Replying to Mr Howlin, and the Fine Gael deputy leader, Mrs Nora Owen, Ms Harney said she was certain that the Taoiseach, who was in Portugal, had been briefed on the matter. "Any action the governments can take on this matter will be taken. It might not always be wise to make public statements on this issue."