Japan expressed "extreme regret" to the Soviet Union Friday over violations of its airspace by Soviet military planes that forced Japanese fighters to scramble, the Foreign Ministry said.

The ministry said the Japanese representation was made to Georgi E. Komarovski, counselor at the Soviet Embassy in Tokyo, by Kazuhiko Togo, director of the Foreign Ministry's Soviet Affairs Division.Komarovski said he would ask Moscow to investigate the incident, a Foreign Ministry spokesman said.

Japan's Defense Agency said "a large-sized" military aircraft, believed a Soviet TU-16 Badger, twice violated Japanese airspace north of Rebun Island off the northwest coast of Japan's northernmost main island of Hokkaido early Friday.

A pair of F-15 fighters scrambled from Chitose Air Base on Hokkaido in each case but the Soviet aircraft was gone when the fighters arrived at the scene, a spokesman for the Defense Agency said.