There would be up to 1,200 extra voters in the Taoiseach's constituency if provision was made for prisoners to vote.

The Minister for Justice, Mr O'Donoghue, agreed that the figure could have a major impact on an election and that "canvassing would be interesting". However, he pointed out that a decision had yet to be made on whether the Government would appeal a High Court judgment in July that the State unfairly discriminated against prisoners by not providing the facilities for them to vote.

Labour's justice spokesman, Mr Brendan Howlin, who raised the issue during Question Time, said between Arbour Hill and Mountjoy Prison there would be 1,200 registered voters "who would constitute a significant portion of a quota and might impact on the outcome of the election" in Mr Ahern's Dublin Central.

Mr O'Donoghue said prison rules did not prohibit the right of a prisoner to vote. They were deemed under electoral legislation to live at the address they were at before imprisonment. However, it would be "prohibitive" for the Prison Service to allow them to vote at their home polling station.

A file on allegations against gardai in Donegal was with the Director of Public Prosecutions, Mr O'Donoghue said.

He said the main issues addressed in an investigation by an assistant Garda commissioner related to the investigation into Mr Richard Barron's death and the role of various gardai in that investigation, allegations of harassment amounting to criminal behaviour, and claims that certain gardai were involved in "hoax" bomb-making equipment finds.

The Minister said the question of the alleged tapping of phones had also been raised by way of complaint to the Law Society and the Bar Council. "In this regard, I am informed by the Garda authorities that they have been in contact with the solicitors in question requesting clarification on a number of matters."