Aircraft wreckage has been found in the North Sea just hours after a U.S. fighter plane crashed off the UK coast on Monday.

The plane is believed to have crashed 74 nautical miles off England's east coast but search and rescue teams are still looking for the missing pilot and the cause of the crash remains unknown.

A U.S. Air Force (USAF) statement said the F-15C Eagle from the 48th Fighter Wing was on a routine training mission from RAF Lakenheath, with one pilot on board, when it crashed off the northeast coast of England at 09:40 local time.

A spokeswoman for the UK's coastguard said: "The HM Coastguard helicopter from Humberside has been sent along with Bridlington and Scarborough RNLI lifeboats.

"Following a Mayday broadcast by HM Coastguard, other vessels nearby are heading to the area."

Colonel William Marshall, commander of the 48th Fighter Wing, said: "Search-and-rescue efforts are currently under way, but the pilot of the aircraft is still missing.

"We will provide updates as they become available, while prioritizing respect and consideration for the pilot's family.

"We are extremely grateful for the timely response of our UK counterparts in the support of these recovery efforts and remain hopeful that our Liberty Wing airman will be located and recovered."

The model of fighter jet is said to have an "exceptional" safety record. 

RAF Lakenheath is the largest US Air Force-operated base in England and home to its only F-15 Fighter Wing in Europe.

More than 4,000 US service men and women are stationed there.