A bruising round of negotiations in Brussels has failed to secure agreement on a proposed €138 billion European Union budget for 2013.

The talks broke down after the European Commission identified a €9bn shortfall in projects already agreed.

However, its recommendation that new money from member states cover the shortfall was refused.

All sides will return to Brussels on Tuesday, with the deadline for agreement set for that night.

The development does not bode well for this month's EU Leaders’ Summit on a seven-year, €1 trillion budget.

Ireland was represented at the talks by Minister of State Brian Hayes, who characterised them as very difficult.

However he said he remains "relatively confident" that a deal can be reached on the 2013 budget before Tuesday's deadline.

Speaking to RTÉ News, Mr Hayes said the EU would be "in very difficult territory indeed" if it was not possible to reach a compromise by then.

He expressed disappointment that the talks had been suspended this evening, but added he felt there was a willingness to have the differences resolved.

Mr Hayes said Ireland's key priorities of agriculture, job creation and education would be protected.

In the 2011 budget, Ireland contributed €1.4bn but received €2bn back from Brussels.

While Ireland will continue to be a net recipient from the EU, it is currently unclear by just how much in 2013.

Informal discussions will now take place over the weekend, before ministers return to Brussels on Tuesday.

Britain's Deputy Prime Minister Nick Clegg has said a huge leap in the EU's annual budget, in what he called an unpredictable way, was not something that many people would welcome.

Speaking in Dublin before the EU budget negotiations broke down, Mr Clegg said it was important that the EU and its institutions abided by the same principles as everyone else at a time when ordinary people had to tighten their belts because of the economic situation.