As we have been reporting, Russia claims 65 Ukrainian prisoners of war were on the military transport plane that crashed in Belgorod.
The local governor has said everyone on the flight has died.
Ukraine is yet to confirm that is the case, and has urged people to "refrain from spreading unverified information".
Mark Voyger, former special adviser for Russian affairs to the US Army Europe, told Sky News the information being released is "sketchy" and it is "highly unlikely" any prisoners of war were on board.
"We can safely rule out that the plane was carrying PoWs," he said.
The crashed plane is an expensive model, typically used by Russian air defence, he said.
He compared carrying PoWs in such an aircraft to "using a helicopter to go shopping".
The trajectory of the plane at the time it crashed has also been questioned, he said, adding that initial data suggests it was flying north and not towards the Ukrainian border as Russia has claimed.
