An unidentified submarine was found in the Japanese waters Wednesday morning, Chief Cabinet Secretary Hiroyuki Hosoda said .

The submarine was spotted in Japan's territorial waters near Miyako and Ishigaki islands in the southern Okinawa Prefecture, according to the top spokesman.

The submarine has left the Japanese waters, Hosoda said, adding Maritime Self-Defense Force's P-3C surveillance aircraft has been sent to trace the submarine.

The Defense Agency has also issued order to step up security measures in the area.

Source: Xinhua