The existing European rescue fund now in place is not large enough to protect Italy as it was never designed to do that, an unnamed European Central Bank source was quoted telling Die Welt newspaper on Sunday.

The existing rescue fund in Europe is not sufficient to provide a credible defensive wall for Italy, the central bank source was quoted telling the newspaper in an advance text of an article to appear on Monday.

It was never designed for that, the source added.

The newspaper said that the rescue fund might have to be doubled to up to 1.5 trillion euros. But it was not clear if it was the central bank source calling for the increase.

There was a sharp sell-off in Italian assets on Friday, which has increased fears that Italy, with the highest sovereign debt ratio relative to its economy in the euro zone after Greece, could be next to suffer in the crisis.

(Reporting by Erik Kirschbaum and Scot Stevenson)