TOKYO, Aug 17 (Reuters) - Hong Kong-based buyout firm Baring Private Equity said on Monday it has offered to buy Japan's nursing home operator Nichiigakkan at 2,000 yen ($18.77) per share.

Nichiigakkan has agreed to be bought by the U.S. buyout firm Bain Capital and Bain's offer is set to expire on Monday.

Baring Private Equity said in a statement it has not yet gained support from the management of Nichiigakkan for its offer. ($1 = 106.5400 yen) (Reporting by Junko Fujita; Editing by Jacqueline Wong)