ECB Executive Board member Joerg Asmussen also told La Stampa daily that Italy had made great progress in terms of improving its public finances, but had now to address the problem posed by its near-zero potential growth.

"There are several practical issues to solve to get to a (unified) European banking supervision," Asmussen was quoted as saying. "I believe that European supervision will be fully operational only during 2013."

EU leaders agreed at the end of June to set up a single banking supervisor in Europe as a pre-condition to letting the euro zone's rescue funds directly inject cash into lenders, without lending to a government first.

Asmussen said Spain, which has requested aid for its troubled banks, would likely experience a temporary increase in its public debt.

"As soon as the new mechanism is in place, the credit would be transferred. The increase in (public) debt would be temporary."

Asmussen said the ECB believed it was important to ensure that its new role as banking supervisor was clearly separated from its monetary policy mandate.

"We must make sure this is guaranteed through distinct decisional and organisational processes," he said.

Asked if Italy could continue to face the euro zone debt crisis without tapping international aid, Asmussen said: "I think Italy can manage by itself if it advances without delays on the reform path and if tackles its growth problem in a serious way."

He said some international institutions have indicated Italy's growth potential is currently close to zero.

"Italy must grow," he said. "Acting solely on the side of public finances is not enough."

Asmussen said he was worried by a growing rift between northern and southern Europe, when asked about German media describing the outcome of the latest EU summit as a defeat for Chancellor Angela Merkel.

"We must ask ourselves only if Europe won. But this way of looking at things is disappearing."

(Reporting by Valentina Za; Editing by David Holmes)

• A Permanent Economic Emergency