SAO PAULO, Aug 31 (Reuters) - The board of Itaú Unibanco Holding SA, Brazil's largest private bank, approved a new share buyback program, the company said in a securities filing on Thursday.

According to the bank, the new program is entitled to buy back up to 60 million ordinary shares and up to 39.15 million preferred shares. The repurchased shares could be maintained at the company, could be canceled or could be put up for sale in the market again, said the filing. (Reporting by Marcelo Teixeira; Editing by Sandra Maler)