Ireland may vote against a landmark trade deal between the EU and a number of South American countries after a strong backlash from Irish farmers.

Last week the EU and Mercosur – a regional alliance of Brazil, Argentina, Paraguay and Uruguay – announced the trade breakthrough following two decades of negotiations.

The deal drew furious reaction from Irish farmers concerned about a potential surge of beef imports into Europe, with the Irish Farmers Association warning the consequences of the deal could be worse than a no-deal Brexit.

Ireland does not have a veto on the deal when it comes to a vote at the European Council in about two years’ time. The vote will be by qualified majority, so Ireland would have to assemble support from close to a third of member states if it wants to defeat the measure.

One senior Government source said it plans to carry out a full assessment of the plan, looking at what the overall impact will be on the Irish economy and jobs. If the results of the assessment are not positive, voting against the deal cannot be ruled out, the source said.

Speaking in Brussels on Sunday, Taoiseach Leo Varadkar said it was “evident” the deal would be bad for the beef sector.

“We need to get an economic assessment of the deal to see what impact it will have on the Irish economy, and if it’s a negative impact on the Irish economy and jobs then obviously we’ll vote against it,” he told journalists on his way into the European Council. “If it has a positive impact well then we’ll be minded to vote for it.”

The economic assessment, he said, would show the deal “good for the dairy and the drinks industry, SMEs and the services sector”.

Minister for Agriculture Michael Creed described the deal as “very disappointing for the Irish beef sector”. He said that notwithstanding the fact it does not allow for the Mercosur countries to start selling the 99,000 tonnes of South American beef into the EU for another 10 years, it was a source of great concern to the Government.

“We already have a European beef market that’s in marginal oversupply and given all the uncertainty about Brexit and the UK, where we sell 300,000 tonnes of Irish beef annually, this deal is very disappointing for us.”

Mr Creed said it appeared the deal on beef was “the sweetener” to get agreement on the entire trade deal which also involves goods such as cars, car parts, pharma and farm products, as well as services and public procurement.

Fianna Fáil is seeking an emergency debate on the issue in the Dáil this week.

Asked if the deal would affect his intention to nominate agriculture commissioner Phil Hogan for reappointment, the Taoiseach repeated his previous statement that the nomination would only be considered by the Cabinet when the new European Commission president is appointed.