(DUBLIN) - Some 10,000 Irish farmers brought Dublin to a standstill Thursday to protest against EU trade proposals during a visit by the President of the EU Commission Jose Manuel Barroso.

Barosso was in the capital to campaign for a "yes" vote in a crunch upcoming referendum on the Lisbon Treaty, which Ireland's plebiscite could theoretically torpedo.

One of the biggest farmer demonstrations for years caused gridlock in the centre of the capital as Barroso held talks with Prime Minister Bertie Ahern and attended a special forum on Europe.

Passions are rising ahead of a June 12 referendum on the Lisbon Treaty. Ireland is the only EU state to vote on it, and could in theory scupper the treaty altogether.

Padraig Walshe, president of the Irish Farmers Association said farmers could not support a Commission "that has sold out on family farming and food production right across Europe."

The farmers claim the stance EU Trade Commissioner Peter Mandelson is taking in the current negotiations on world trade Geneva could virtually wipe out the beef and dairy sector.

In the past farmers have been strong supporters of the EU and have been big financial beneficiaries from the Common Agricultural Policy (CAP).

But Walshe, whose body represents some 85,000 farm families, said that if the Mandelson proposals were followed there would not be farmer support for the treaty.

"That is my message for President Barroso today," he told RTE state radio, "That is my message for the government today."

He claims the outcome of the current negotiations would cost the Irish economy 4 billion euros (6.3 million dollars) and see 50,000 farmers put out of business, along with 50,000 job losses in the processing sector.

In 2001, Ireland sent shockwaves through the bloc when it rejected the EU's previous Nice Treaty on institutional reform and enlargement. That decision was reversed in another referendum in 2002.

A poll published Monday showed that a vast majority of Irish voters remain undecided: 28 percent plan to vote "Yes", 12 percent "No" and 60 percent are still to make up their minds, according to the poll in the Irish Sun newspaper.

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