RBI, which has said losses could exceed 500 million euros (373 million pounds) in 2014, said late on Wednesday that it was planning to extend its capital buffer by reducing its risk-weighted assets (RWA) by at least 20 percent.

Shares in the bank rebounded more than 10 percent to 9.940 euros by 9:45 a.m., having hit a new low on Wednesday.

"We are not in a rush," Martin Gruell told a call with analysts, saying the asset reduction was a medium-term project. He said the Austrian bank would give firm details when it releases preliminary 2014 results next month.

RBI also reiterated it was not planning to sell its Russian unit or carry out a capital increase. Its equity and total capital ratios fulfilled all regulatory capital requirements, it added.

RBI operates in Austria and 15 countries in central and eastern Europe, but also has branches in other countries. RBI's business in 2014 suffered particularly in Ukraine and Hungary.

(Reporting by Michael Shields; editing by David Clarke and Keith Weir)