Ireland may have to hold a referendum on building a fiscal union in the euro zone, the minister for European Affairs said on Friday.

I would say it's 50-50 and we will be looking at the detail over the next couple of weeks, Lucinda Creighton told Reuters by telephone from Brussels, where she is attending an EU summit.

Twenty-three of the 27 EU leaders have agreed to pursue tighter integration with stricter budget rules for the euro zone at the summit but Britain, a key trading partner for Ireland, said it could not accept proposed amendments to the EU treaty after failing to secure concessions for itself.

Creighton also said she expected the ECB to act more decisively in the weeks ahead with its bond-buying programme. There will be a continued need for the ECB to be pro-active in the market in order to continue to try and stabilise the currency, she said.

(Reporting by Carmel Crimmins)