Dublin  - An opinion poll published in the Sunday Business Post shows a marked swing among Irish voters against the EU's Lisbon Treaty, which aims to streamline decision-making in the 27-member bloc.

Sunday's Red C poll found that 35 per cent of eligible voters support the treaty, down eight percentage points since the last survey, while 31 per cent are against it, up seven points.

A third of voters are undecided. Without the undecided voters, the yes campaign leads by just six points, with 53 per cent for the treaty versus 47 per cent against.

Ireland is the only EU country to vote in a referendum to ratify the reform treaty that replaced the EU constitution rejected by Dutch and French voters. The vote is scheduled for June 12.

Red C said in particular Irish farmers, who recently demonstrated in Dublin during a visit by European Commission President Jose Manuel Barroso, had shifted against the treaty.

The farmers are concerned that EU Trade Commissioner Peter Mandelson is not defending their interests in upcoming World Trade Organization talks.

Europe Minister Dick Roche told national broadcaster RTE that all was "very much to play for" as the political campaign could not start until the referendum bill had been finalized by parliament.

Anti-treaty group Libertas told RTE the vote swing showed that "its concerns over taxation, democracy and accountability are resonating with the electorate." (dpa)