A US air force F-15 fighter jet has crashed into the Pacific Ocean off the southern Japanese island of Okinawa after the aircraft developed technical problems in flight.

A US air force spokesperson said the pilot ejected safely from the jet and was recovered by a Japanese air force helicopter.

The F-15, flying out of Kadena Air Base, went down in the Pacific about 70 miles east of Okinawa, the military said.

Lt Col David Honchul, the chief spokesman for the US forces in Japan, said the pilot was recovered after a search by US and Japanese rescue crews.

After he ejected from the plane the pilot, whose name has not been released, remained in contact with rescuers. After being airlifted by a Japanese helicopter, he is now in a stable condition at a military hospital on Okinawa.

The cause of the crash is under investigation.

The US military has about 50,000 troops based in Japan, about half of these on Okinawa.

Kadena is one of the largest US airbases in the Asia-Pacific region. The F-15 was attached to Kadena's 18th Wing.

The crash was the first for an F-15 based at Kadena since January 2006.