Istanbul: NATO is preparing to convene an emergency meeting in Brussels overnight as tensions between Turkey and Russia intensified after Turkey confirmed two of its F-16s downed a Russian fighter jet they said violated Turkish airspace.

The jet crashed in a mountainous area in Syria just kilometres from where it is alleged to have violated Turkish airspace near the border region of Yayladagi, the Turkish military said.

It is the first major loss suffered by Russia since it entered the bloody years-long Syrian civil war with a series of air strikes on September 30 and has raised fears of an ever deepening conflict in a region already gripped by violence.

President Vladimir Putin called Turkey's downing of a Russian fighter jet "a stab in the back" carried out by the accomplices of terrorists, saying the incident would have serious consequences for Moscow's relations with Ankara.

"Our plane was shot down on Syrian territory by an air-to-air missile from an F-16. It fell on Syrian territory 4 kilometres from the Turkish border. It was flying at 6000 metres 1 kilometre from Turkish territory when it was attacked."

Putin said Russian pilots and planes had in no way threatened Turkey, but had merely been carrying out their duty to fight Islamic State militants inside Syria.

"We established a long time ago that large quantities of oil and oil products from territory captured by Islamic State have been arriving on Turkish territory," he said, saying that was how militants had been funding themselves.

"And now we get stabbed in our back and our planes, which are fighting terrorism, are struck. This despite the fact that we signed an agreement with our American partners to warn each other about air-to-air incidents and Turkey ... announced it was allegedly fighting against terrorism as part of the US coalition."

Turkey is one of the most popular holiday destinations for Russians, and the two countries enjoy active diplomatic relations.

Foreign Minister Sergei Lavrov is due to visit Turkey on Wednesday, in a trip arranged before the incident, while Turkish President Tayyip Erdogan is scheduled to visit Russia for talks with Putin in December.

Putin expressed anger at Turkey's decision to convene a meeting of NATO to discuss the incident, suggesting Ankara should instead have swiftly tried to contact Moscow.

"It's as if we shot down a Turkish plane rather than them shooting down one of ours. What do they want? To put NATO at Islamic State's disposal? We will never tolerate such crimes like the one committed today.

For many observers, the possibility of Russia and Turkey facing off in the air was all but inevitable given Turkey's continued insistence that Syria's President Bashar al-Assad must step down and Russia's aggressive backing of the Assad regime.

The skies above Syria area already crowded - along with Russian and Syrian war planes, there are several nations flying sorties over Syria as part of the US-led coalition against the Islamic State, of which Australia is a member.

NATO confirmed it was to hold an emergency meeting late on Tuesday over the incident, while Turkey announced it had summonsed the Russian ambassador over the affair.

There were several unconfirmed reports that both pilots - who were reportedly seen in videos parachuting from the stricken jet - died in the crash.

Citing sources from a Free Syrian Army brigade in the Bayirbucak area where the jet is believed to have crashed, Charles Lister, a visiting fellow and jihadist expert at Brookings Doha Centre said both pilots had died.

CNN Turk reported that at least one of the pilots who parachuted from the stricken jet had been captured by fighters from the Turkmen minority who inhabit the region – mostly Syrians of Turkish origin.

Video circulating on social media – unable to be verified by Fairfax Media – appeared to show a dead soldier, thought to be in Russian military uniform, surrounded by locals.

The region in which the Russian jet went down – known as the Turkmen Mountains or Jabal al-Akrad – borders Syria and Turkey and has allegedly been subjected to a series of Russian airstrikes over the last week that has forced thousands from the Turkmen minority to flee into Turkey, human rights groups say.

Turkey had already requested an urgent meeting of the United Nations Security Council over the airstrikes on the Turkmen region after at least 1500 civilians fled their homes in Syrian over the border into Turkey on Saturday following the attacks.

The Turkish military says the jet brought down after violating Turkish airspace was given 10 warnings over a five-minute period, Turkey's military said Tuesday.

The military did not specify the type of plane but Turkish presidential sources and the Russian Ministry of Defence have identified the aircraft as a Russian SU-24.

- with Reuters