The plane, from RAF Leuchars in Fife, was on a training flight when it hit a hillside at 11.45am in Glen Kinglas, Argyll.

An MoD spokesman said: "It is with deep regret that the Ministry of Defence must confirm the deaths of two RAF air crew from 43 Squadron.

"The next of kin have been informed and have requested a period of 24 hours grace before further details are released."

The Tornado F3 came down near a tourist spot known as the Rest And Be Thankful on the A83 Arrochar to Inveraray Road, northwest of Loch Lomond.

No civilians are understood to have been hurt.

Search and rescue helicopters from the HMS Gannett naval base and RAF Lossiemouth were scrambled to search the area for the wreckage and crew.

An RAF spokesman said there had been a small blaze at the scene which the fire service dealt with.

Air accident investigators will try to establish the cause of the crash which happened when the weather was said to be overcast.

Witness Andy Graham, 60, described how he saw two Tornados flying low in the area around lunchtime.

"We get jets flying over here on training exercises quite regularly. It's not unusual to see them and you definitely hear them," he said.

"But today they seemed to be flying much lower than normal. We watched them fly along the loch, up through the glen and towards the Rest And Be Thankful."