A British F-35 fighter jet has crashed into the sea during a routine operation in the Mediterranean, the country's Ministry of Defence said Wednesday.

The pilot ejected and returned safely to the royal navy aircraft carrier HMS Queen Elizabeth, the ministry said.

It added the incident happened at 10:00 GMT over international waters and hostile action is not thought to have been involved. 

An investigation has begun and would likely focus on potential technical or human error, reported the BBC.

There are eight British F-35 jets on the carrier and 12 from the U.S. Marine Corps.

The supersonic fighters, which cost 92 million pounds (about 124 million U.S. dollars) each and are built by the U.S. firm Lockheed Martin, are based at RAF Marham in Norfolk, according to the BBC.