Weakened by decades of mismanagement, Carige risks collapse as a result of bad loans accumulated during a deep recession that followed the global financial crisis a decade ago.

In January, the European Central Bank placed the Genoa-based bank under special administration and told it to find a buyer.

After at least two bailout plans fell through, the ECB has given Carige until July 25 to come up with a solution. A source with knowledge of the matter said its administrators were working to meet that deadline.

Under the latest rescue plan, a depositor protection fund (FITD) financed by Italian banks would inject some 520 million euros including by converting into equity a 320 millions euro bond bought from the bank last year, according to the sources.

The sources said Cassa Centrale Banca, an unlisted cooperative bank based in northern Trentino region, could provide some 80 million euros, while two state-owned banks, Credito Sportivo and Mediocredito Centrale, could help by underwriting up to 200 million euros in convertible bonds.

A source close to the FITD said on Monday Cassa Centrale Banca was expected to take an initial stake of just under 10%.

Up to 100 million euros of the cash call could be reserved for current shareholders of Carige.

The lender's top shareholder, the Malacalza family, could pitch in. It has already invested more than 400 million euros in Carige since 2015 and now owns 27.5% of the bank.

Carige, FITD, Cassa Centrale Banca, Mediocredito Centrale, Credito Sportivo and Malacalza declined to comment.

Carige's administrators in February unveiled a 630 million euro capital shortfall, but a new business plan calls for a much bigger clean-up of Carige's bad loans, requiring a larger capital injection, one of the sources said.

The deal needs to be approved by Carige's shareholders, meaning the position of the Malacalza family will be key.

At the start of the year the family, which made its fortune in steel, blocked a proposed cash call, a move which prompted the ECB to place the lender under special administration.

One of the sources said two private investors could also join a rescue, easing the burden on Italian banks and Carige's shareholders.

On Monday, FITD chief Salvatore Maccarone said its shareholders would vote on July 23 on the planned conversion of Carige bond.