A British F35 jet from the UK's flagship aircraft carrier crashed into the Mediterranean while flying and the pilot ejected, the Ministry of Defense said on Wednesday.

"A British F35 pilot from HMS Queen Elizabeth ejected during routine flying operations in the Mediterranean this morning," the ministry said.

"The pilot has been safely returned to the ship and an investigation has begun, so it would be inappropriate to comment further at this time."

The incident is the first such one to affect the HMS Queen Elizabeth, which was on its way back to the UK after more than seven months at sea on a maiden trip to the Far East and back.

No hostile action is believed to be involved in the incident which occurred over international waters.

The jet, which costs around £100 million, has not yet been retrieved from the sea, where it is believed to be.

Local media reported that the investigation is likely to focus on potential technical or human error.

Eight British F35 jets are on the carrier, along with 10 American F35s. All other F35 operational and training flying continued.

(With input from agencies)