European Union building in Brussels, Belgium.

Euro zone leaders intend to scale up their emergency fund, the European Financial Stability Facility, to around 1.0 trillion euros, EU sources said on Wednesday.

The sources said the 440 billion euros ($611.4 billion) fund, set up last year, would have about 250-275 billion euros available after amounts are set aside for aid to Greece, Ireland and Portugal and for the recapitalizing the region's banks.

That amount would be scaled up around four times, arriving at a headline figure of around 1.0 trillion.

"The ratio of the leverage will be of at least 4 times," one source said, while another said the spare capacity available to be leveraged was 250 billion to 275 billion.