One of two pilots aboard a Russian war plane shot down by Turkey this morning was killed by fire from the ground after he parachuted from the craft, the Russian military said this evening.

It was citing what it said was preliminary information.

"The plane fell in Syrian territory, four kilometres from the border. The crew ejected.

"According to preliminary information, one of the pilot died after being fired upon from the ground," military spokesman General Sergei Rudskoi said in televised remarks.

A Russian soldier was also killed during a failed operation to rescue the two pilots, Russia announced earlier.

"A search and rescue operation to evacuate the Russian pilots from the crash site was launched with the help of two Mi-8 helicopters," military spokesman General Sergei Rudskoi said in televised comments.

"During the operation, one of the helicopters was damaged by gunfire and had to land. A soldier was killed."

Russian President Vladimir Putin earlier branded the downing of the plane a "stab in the back" committed by "accomplices of terrorists".

He added: "Today's tragic event will have serious consequences for Russian-Turkish relations."

He was speaking during a televised meeting with Jordanian King Abdullah II in the Black Sea resort of Sochi.

"We will of course carefully analyse everything that happened," he said.

Turkish fighter jets shot down the plane near the Syrian border after repeated warnings over air space violations, but Russia said it could prove the jet had not left Syrian air space.

A Russian government spokesman said it was a "very serious incident" but that it was too early to draw conclusions.

Footage from private Turkish broadcaster Haberturk TV showed the warplane going down in flames in a woodland area, a long plume of smoke trailing behind it. The plane went down in area known by Turks as "Turkmen Mountain", it said.

Separate footage from Turkey's Anadolu Agency showed two pilots parachuting out of the jet before it crashed.

The Turkish military said the aircraft had been warned ten times in the space of five minutes about violating Turkish air space. Officials said a second plane had also approached the border and been warned.

"The data we have is very clear. There were two planes approaching our border, we warned them as they were getting too close," a senior Turkish official told Reuters.

"We warned them to avoid entering Turkish airspace before they did, and we warned them many times. Our findings show clearly that Turkish airspace was violated multiple times. And they violated it knowingly," the official said.

Turkish President Tayyip Erdogan was briefed by the head of the military, while Prime Minister Ahmet Davutoglu ordered consultations with NATO, the United Nations and related countries, their respective offices said.

The Syrian Observatory for Human Rights monitoring group said the warplane crashed in a mountainous area in the northern countryside of Latakia province, where there had been aerial bombardment earlier and where pro-government forces have been battling insurgents on the ground.

The so-called Islamic State militant group, which has beheaded foreign captives in the past, is not known to have a presence there.

NATO chief Jens Stoltenberg said this evening that the military alliance stands by Turkey over the incident.

"As we have repeatedly made clear, we stand in solidarity with Turkey and support the territorial integrity of our NATO ally, Turkey," Mr Stoltenberg said after an emergency meeting of all 28 members requested by Turkey.

"I look forward to further contacts between Ankara and Moscow and call for calm and de-escalation. Diplomacy and de-escalation are important to resolve this situation," he said.