Japan says an unidentified ship spotted Wednesday near Japanese waters resembled a North Korean spy vessel. But the Japanese are not going to let the incident interfere with the coming meeting between Prime Minister Junichiro Koizumi and North Korean leader Kim Jong Il.

Officials in Tokyo are downplaying the incident, which comes less than two weeks before Japan's Prime Minister is to make an unprecedented trip to North Korea.

The Japanese were alerted to the intrusion by U.S. intelligence, which reported that an unidentified vessel emitting unusual radio signals had entered Japan's air defense zone. The Japanese dispatched a destroyer, 15 Coast Guard vessels and a patrol plane to the Sea of Japan. The Japanese Coast Guard said it spotted a ship with North Korean markings. The 35 meter long ship then turned and sailed out of the defense zone, and early Thursday the Japanese vessels gave up the chase. Japanese foreign minister Yoriko Kawaguchi initially told reporters the vessel had raised suspicions, but then Japanese comments about the incident became more guarded.

Prime Minister Koizumi, returning from the U.N. environment summit in South Africa, entered his office without commenting on the case. Government spokesman Yasuo Fukuda told reporters Thursday that the incident would not impair this month's meeting between Mr. Koizumi and the North Korean leader. But the chief cabinet secretary did say the issue of North Korean ships in Japanese waters will be raised when Mr. Koizumi meets North Korea's Kim Jong Il in Pyongyang on September 17.

Over the years, vessels believed to be from North Korea, have been tied to spying and drug running in Japan.

Officials say this latest vessel closely resembled the suspected North Korean spy ship that was sunk off Japan last December after a fierce gun battle with the Japanese Coast Guard. Japan is in the process of raising that ship.