A Russian military cargo plane has crashed as it came in to land at an air base in Syria, killing all 39 people onboard, Russia's Defence Ministry said.

The Russian military said an An-26, with 33 passengers and six crew members aboard, crashed 1,600ft from the runway. The military blamed the crash on a technical error.

Russia, a key ally of Syrian President Bashar Assad, leases the Hemeimeem military base in Syria, near the Mediterranean coast.

The base is far from the front lines of the conflict, but came under shelling in December.

The Russian military insisted the cargo plane did not come under fire, but said it would conduct a full investigation. The military did not immediately identify the victims.

President Vladimir Putin offered his condolences to the families of those killed in the crash after receiving a briefing from defence minister Sergei Shoigu, the Kremlin said in a statement.

The Interfax news agency quoted a spokeswoman for Russia's Investigative Committee, which handles high-profile cases, as saying Russian investigators have been dispatched to Syria to look into the crash.

It was the second Russian military plane to crash in Syria this year, after a Su-25 ground attack jet was struck by a portable air defence missile over Idlib province last month.

The Antonov An-26 is a twin-engined transport plane designed in the late 1960s in the Soviet Union. Large numbers have remained in service in Russia and other countries around the world.

An An-26 belonging to a military flight school crash-landed and caught fire south east of Moscow in May last year, killing one crew member.