A deputy commander of a Turkmen brigade has claimed that his forces shot dead the two pilots of a Russian bomber downed by Turkish F-16 fighter jets near the border with Turkey as they descended with parachutes.

Alpaslan Celik, deputy commander in a Syrian Turkmen brigade, told Reuters that both pilots "were retrieved dead". "Our comrades opened fire into the air and they died in the air," he said.

Meanwhile, Russia's Foreign Minister Sergei Lavrov has cancelled a planned visit to Turkey after the downing of the Su-24 on 24 November. Speaking to reporters in Sochi, Lavrov warned Russians not to visit Turkey saying the threat of terrorism there is no less than in Egypt.

Turkey's fighter jets shot down the warplane, a Russian Su-24, after repeatedly warning it over air space violations, according to Turkish officials. The military said the downed jet was warned 10 times in five minutes before being shot down by its own F-16 fighter jets.

Russia's President Vladimir Putin has called Turkey's downing of the warplane a "stab in the back by the accomplices of terrorists" such as Islamic State (Isis).

The incident took place as the Syrian Observatory for Human Rights (SOHR), a UK-based monitoring group, reported that Syrian rebels destroyed a Russian helicopter with a missile. An insurgent group, which receives US Tow missiles, said its fighters hit the helicopter while it was in the air and published a video showing the same copter being blown up after one fighter strikes it with another missiles.

The report could not be independently verified.