Fine Gael and the Labour Party have said that they intend to raise what they say are new concerns about the Taoiseach's tax affairs when the Dáil returns next month.

Both parties said that a report in the 'Irish Mail on Sunday' newspaper raised extremely serious issues concerning Taoiseach Bertie Ahern's dealings with the Revenue Commissioners.

The Labour Party leader Eamon Gilmore said that Mr Ahern's credibility was being undermined and his authority was being eroded by each new revelation about his finances.

The Fine Gael Justice Spokesperson, Senator Eugene Regan, said it was now time for the Taoiseach to come clean on all matters relating to his tax affairs.

A spokesman for Fianna Fáil said that issues relating to the Mahon Tribunal should be dealt with by the tribunal and that matters relating to the tax affairs of any individual should be dealt with by the individual concerned and the Revenue Commissioners.