Speaking to reporters in Brussels, Monti said the European Stability Mechanism, due to become effective in July, needs to be increased but he refused to confirm reports that he had asked for a capacity of 1 trillion euros.

"If the amounts are of sufficient size that markets consider them credible then it is very probable that they will never have to be spent," he said.

(Reporting by Francesca Landini, writing by Gavin Jones)