The central bank took control of Corpbank, Bulgaria's fourth biggest lender, in June and closed down its operations after a run on deposits triggered the country's worst banking crisis since the 1990s.

In a statement, the central bank said it had extended supervision for two months until Nov. 20. It said a solution was not possible until a clear estimate of the bank's asset quality and capital adequacy due by Oct. 20.

The bank invited shareholders and potential investors to offer concrete proposals for the bank's rescue between Oct. 28 and Nov. 20.

(Reporting by Tsvetelia Tsolova; Editing by Matt Robinson)