Businessman Declan Ganley has said he will campaign against the fiscal treaty because he feels it does not deliver a deal on Ireland's bank debt.

He said it would be irrational to vote Yes to what he said would be bank debt that we have no moral responsibility for and he said there would be no economic recovery without such a deal.

Mr Ganley, who previously said he was undecided on the referendum, said he had to wait to allow European partners to respond to calls for a deal on bank debt. In the absence of a deal, he said he is now advocating a No vote.

He said Libertas no longer existed as a political party and was now a think tank, but it would have a "limited poster campaign". Asked about his lack of mandate as an unelected representative, Mr Ganley said the truth had no mandate.

Minister for Agriculture and director of Fine Gael’s referendum campaign Simon Coveney dismissed Mr Ganley's suggestion that a No vote would help Ireland get a better deal on bank debt.

Mr Coveney said rejecting the treaty would have the opposite effect and would damage Ireland’s capacity to secure better terms on bank debt.

Meanwhile, Socialist Party MEP Paul Murphy has said that the Government's campaign for the fiscal treaty has consisted overwhelmingly of scaremongering about access to second funding and that this seems to have had some impact.

Mr Murphy was commenting on the results of an opinion poll published in today's Sunday Business Post newspaper, which shows support for the treaty has increased significantly over the past fortnight.

The Red C poll of 1,000 voters found that 53% said they would vote Yes, an increase of six points on the last poll a fortnight ago.

When undecided voters are excluded the Yes side leads by 63% to 37%.

Tánaiste Eamon Gilmore gave a cautious welcome to the opinion poll results.

Speaking at a James Connolly commemoration in Dublin, Mr Gilmore said the Government was mindful of the lessons of past elections and would continue to campaign up until polling day.

On Declan Ganley, Mr Gilmore said he was not surprised by his intervention but he said any deal on the bank debt was a separate set of negotiations.

Asked if the Government was burying bad news until after polling day, Mr Gilmore said they were continuing as normal.

Taoiseach Enda Kenny said that what is important now for the Yes side in the referendum is to explain the magnitude of the decision and what is in the fiscal treaty and what is not.

Speaking in Drogheda at a famine commemoration, Mr Kenny said that he did not comment on opinion polls.

Asked about Declan Ganley's intervention, he said it was a free country and everyone was entitled to their viewpoint although he said bank debt was not the issue and the treaty was about good housekeeping.