Two aircrew were killed on Thursday when a Russian Su-24 Fencer attack aircraft crashed at the Ukrainka military airfield in Russia's Far East, military prosecutors said.

"A Su-24 aircraft crashed while landing at about 12.00 local time (02:00 GMT) in the Amur region. Both pilot and navigator were killed in the crash," a statement said.

The plane, which was flying in from the Central Russian city of Voronezh for planned maintenence work, reportedly ran off the landing strip and caught fire after the landing gear collapsed in a heavy landing.

Defense Ministry officials said the crash was caused by a problem with the plane's landing gear.

Safety checks have been ordered on the entire Su-24 fleet, and an investigation has been started into the causes of the crash.

So far, the air forces has not decided to ground the entire Su-24 fleet, which is a common practice in the Russian armed forces after air accidents where technical faults are suspected.