AMSTERDAM - The European bail-out fund should be doubled to 1,500 billion euros ($2.15 trillion) if politicians want private sector investors to participate in a second bail-out package for Greece, a European Central Bank governing council director said.

Nout Wellink told Dutch newspaper Het Financieele Dagblad that a new Greek aid package would carry so many uncertainties and risks that a doubling in the bail-out fund would be necessary to take into account the contagion risk for both Ireland and Portugal.

"If you take these risks, you need to build a safety net," Wellink, who is also the outgoing Dutch central bank president, was quoted as saying on Thursday.

"It should go to 1,500 billion euros and there should be more flexibility in how the money can be spent."

The euro fell to a three-week low of $1.4113 after the report.