Minister for Finance Brian Lenihan has called on Declan Ganley to confirm that a London-based hedge fund said to be backing his campaign does not have a vested interest in a No vote.
Speaking at a news conference this morning, Mr Lenihan said he found it curious that a hedge fund backer would have a direct interest in goings-on in Ireland.
He said it was clear that a No vote would break confidence in Ireland.
It was, he claimed, 'disturbing' that Mr Ganley's only declared backer would be an organisation that did not have Ireland's best interests at heart.
Mr Lenihan also said that Dr Michael Somers, the head of the National Treasury Management Agency, had confirmed that a No vote would increase the cost of Ireland's borrowing.
Speaking on RTÉ's News At One, Mr Ganley described the comments as nonsense and said he had not received support from such a hedge fund in this referendum.
Later, Mr Ganley said that the London based hedge fund donor gave money to the Libertas campaign in Britain last June for the European elections.
He said it was well spent on that campaign and has nothing to do with Ireland's Lisbon referendum.
Mr Ganley said what Minister Lenihan said was a lie and that the Government's whole campaign was based on a lie.
He said it was a distraction, aimed at not talking about the Lisbon Treaty, but talking about something which is six months old and has nothing to do with this campaign.
The Libertas leader said his backers were the ordinary people of Ireland.
Elsewhere, Sinn Féin President Gerry Adams has warned that the Treaty is replete with the kind of right-wing policies that had caused the recession and had led us to the current crisis.
Campaigning in Dublin, Mr Adams insisted it was 'the same treaty, the same Government and the people should give the same answer'.
Taoiseach Brian Cowen has said the context for the referendum has changed dramatically with Ireland's new economic circumstances.
He was speaking at Dromoland Castle this afternoon as a guest of the Shannon Chamber of Commerce.
Mr Cowen said Ireland now has a fragile economic situation and it needed policy initiatives to correct that and aid economic recovery.
He said the decision on Lisbon would be one of the most important that Ireland has had to make since joining the EU in 1973.
Lisbon would have no effect on neutrality - Gormley
Green Party leader John Gormley has said the Lisbon Treaty would have no effect on Ireland’s neutrality and would not force young Irish people into war.
Mr Gormley said there is no room for complacency in the campaign and that the last few days will be crucial.
He said he did not believe there would be a No victory but the outcome will be tight.
Asked about the impact of the FÁS controversy, Mr Gormley appealed to concentrate on the Lisbon Referendum and ensure there was a Yes vote to help our economic recovery.
The minister accused parties on the No side of misrepresenting these issues.
He said nowhere in the treaty does it require Ireland to spent more on military outlays.
He said there are guarantees that Ireland will decide how much to spend on military expenditure - and on how we spend it.
Fine Gael leader Enda Kenny has said he was confident that people would put aside their anger at the Government and distinguish between domestic political issues and the bigger European question.
Mr Kenny said the Irish electorate would have their own referendum on the Government soon enough.
He was speaking in Castlebar tonight during his countrywide campaign to secure a Yes vote.