Tsvetan Vassilev faces charges in Bulgaria after a run on Corpbank, the country's fourth biggest lender, in June prompted the central bank to take control and close its operations.

The central bank said on Tuesday it had extended its supervision over Corpbank until Nov. 20, by which point it said a final decision on the bank's fate should be taken.

Vassilev's lawyer confirmed his client's surrender in the Serbian capital, Belgrade.

"Vassilev presented himself to Serbian authorities," lawyer Konstantin Simeonov told Reuters. "From there, an extradition process will start. The Serbian court has 40 days to decide on the process."

A senior source in the Serbian interior ministry had earlier told Reuters of Vassilev's surrender, based on an international arrest warrant.

AUDIT

Vassilev, locked in a public feud with a rival at the time of the run on Corpbank, has repeatedly denied wrongdoing and blamed the deposit run on a plot hatched by his competitors.

A Bulgarian court on Friday had rejected a motion from Vassilev to have the arrest warrant lifted.

Vienna-based advisory firm EPIC, acting for Corpbank's main shareholders and potential investors, is seeking to start work with the central bank on a rescue plan for the bank, shut since June 20.

EPIC has said it represents Vassilev, who owns 50.6 percent of the bank, as well as an Omani sovereign wealth fund with a 30 percent stake and VTB Capital, controlled by Russia's VTB Bank, with about 9 percent.

Efforts to put together a quick rescue plan have become bogged down pending October elections, and analysts say no solution is likely before a new parliament is set up.

The central bank on Tuesday called on shareholders and potential investors to offer rescue proposals between Oct. 28 and Nov. 20.

It said the results of a full audit of Corpbank's books - carried out by Deloitte, Ernst & Young and local auditor AFA - should be ready by Oct. 20. That will provide the basis for an estimate of the bank's capital adequacy by the end of October.

"Based on the results of the asset assessment of Corpbank, the declared capital adequacy ratio and the declared investment intentions of EPIC, a final decision for Corpbank should be taken between Nov. 1 and Nov. 20," the central bank said.

The central bank has also asked administrators at Bank Victoria, a unit of Corpbank, to seek final offers from other commercial banks for the potential sale of part of the unit's loan portfolio by Oct. 15.

It said the sale may not take place if a rescue proposal by EPIC encompasses Bank Victoria.

(Writing by Matt Robinson; Editing by Sonya Hepinstall)

By Aleksandar Vasovic and Tsvetelia Tsolova