The Chinese embassy in Tokyo received an envelope containing a suspected rifle bullet on Sept. 27 in the name of Japan's Prime Minister, according to Tokyo police, Kyodo News reported.

The police failed to find any threatening content inside the envelope sent under the name of Prime Minister Yoshihiko Noda.

The Tokyo Metropolitan Police Department said it may be a mischievous act regarding the Diaoyu Islands dispute between the two countries. Investigation on the bullet is currently under way.