Japan's Defence Agency said today it had an unconfirmed report that North Korea fired a short-range surface-to-ship missile earlier in the day.
An agency spokesman said that according to the information, the missile was launched from the eastern coast of North Korea at around noon (4 a.m. Irish time) today.
Public broadcaster NHK said the missile was likely to have been a version of the Chinese Silkworm anti-ship missiles that North Korea fired in February and again in March of this year, and which has a range of around 100 km (60 miles).
A South Korean Defence Ministry spokesman said Seoul was aware of the reports about the missile firing but had not confirmed it.
In 1998, North Korea shocked the world by firing a Taepodong ballistic missile that flew over Japan's main island of Honshu and landed in the sea off Japan's Pacific coast.
While Tokyo has downplayed previous North Korean launches of short-range non-ballistic missiles, saying they pose no threat to national security, today's firing is likely to increase international pressure on Pyongyang to exercise restraint, as it comes amid the crisis over its nuclear weapons programme.
The North Korean nuclear crisis was discussed at the summit of Asian-Pacific leaders in Bangkok, where a communique to be issued tomorrow is expected to include a call for the Korean Peninsula to be free of nuclear weapons.