TOKYO, Sept 1 (Reuters) - The Bank of Japan said it bought Japanese government bonds worth 8.186 trillion yen ($56.28 billion) in August, compared with 9.820 trillion yen in July.

The number comes as market players seek signs of the central bank's preparation to phase out its ultra-low rate policy.

Last month the BOJ doubled its de-facto cap on the yields to 1% from 0.5%, allowing the yields to move more freely.

($1 = 145.4600 yen) (Reporting by Junko Fujita and Mariko Katsumura; Editing by Kim Coghill)