The Ministry of Defence in Moscow announced the crash was presumably due to technical causes but Ukraine said the plane had been shot down.

According to Moscow, the aircraft crashed in the Stavropol region of southern Russia while returning from a combat mission. The four crew members had ejected and three have so far been rescued. The aircraft had no ammunition on board, the ministry added.

The reported crash site is around 600 kilometres behind the front line in Ukraine.

Russian and Ukrainian military bloggers shared spectacular but unverified videos on social media which allegedly show the long-range bomber spinning in the air with its engine on fire.

The commander of the Ukrainian Air Force, Mykola Oleshchuk, announced that this was the first time such an aircraft had been successfully shot down with a missile. The claims of both sides regarding the incident could not be independently verified.

According to the Ukrainian Air Force, Russia used several Tu-22Ms in air attacks early on Friday. They fired six cruise missiles at Ukraine but two were intercepted, the statement added.