TOKYO/WASHINGTON • Japan has detected radio signals suggesting North Korea may be preparing another ballistic missile launch, although such signals are not unusual and satellite images did not show fresh activity, a Japanese government source said yesterday.

After firing missiles at a pace of about two or three a month since April, North Korea paused missile launches in September following the firing of a rocket that passed over Japan's Hokkaido island.

"This is not enough to determine (if a launch is likely soon)," the source told Reuters.

Japan's Kyodo news agency reported late on Monday that the Japanese government was on alert after catching the radio signals. It also said the signals might be related to winter military training by the North's military.

North Korea is pursuing its nuclear weapons and missile programmes in defiance of United Nations Security Council sanctions and has made no secret of its plans to develop a missile capable of hitting the United States mainland. It has fired two missiles over Japan.

South Korea's Yonhap news agency, citing a government source, said intelligence officials of the US, South Korea and Japan recently detected signs of a possible launch and have been on higher alert.

South Korean Unification Minister Cho Myoung Gyon yesterday said there have been "noteworthy" movements from the North since its missile launch in September, but there was no hard proof of another nuclear or missile test.

REUTERS