All five people on board a Russian military helicopter that was shot down over Syria on Monday are believed to have died, the Kremlin said.

All five people on board a Russian military helicopter that was shot down over Syria on Monday are believed to have died, the Kremlin said.

The Russian defense ministry said the Russian military helicopter was shot down over the Syrian province of Idlib.

"A Russian Mi-8 military transport helicopter was shot down from the ground in Idlib province after delivering humanitarian aid to Aleppo," the ministry said in a statement.

"There were three crew members and two officers from the Russian reconciliation centre in Syria on board," it said.

Kremlin spokesman Dmitry Peskov expressed condolences over the deaths of the five soldiers.

"As far as we know from the information we've had from the defense ministry, those in the helicopter died, they died heroically, because they were trying to move the aircraft away to minimize victims on the ground," he told journalists.

Photos shared widely on social networks by Syrian opposition on Monday purported to depict the smoking craft in the desert and personal belongings of those inside, including Russian drivers' licenses, passports and insurance cards, as well as Orthodox Christian icons.

The authenticity of the pictures could not be independently confirmed.

The Monday downing brought the toll for Russian soldiers killed in the Syrian conflict to 18.