Nato will hold an emergency session today after Turkey shot down a Russian warplane it claimed had entered its air space.
The North Atlantic Council (NAC) will meet in Brussels in response to the downing of the aircraft by Nato member Turkey.
UK Foreign Secretary Philip Hammond told MPs that officials were urgently seeking details about the incident from Ankara and Moscow.
Nato spokeswoman Carmen Romero said the meeting was called at the request of Turkey.
"The aim of this extraordinary NAC meeting is for Turkey to inform allies about the downing of a Russian airplane," she said.
"Nato is monitoring the situation closely. We are in close contact with Turkish authorities."
Ankara claimed its F-16s shot down the Russian plane after it ignored repeated warnings over the violation of Turkish air space.
But Moscow said the Su-24 jet was downed by artillery fire while on a bombing mission in Syria and had not strayed across the border.
The Russian defence ministry statement said: "We are looking into the circumstances of the crash of the Russian jet. The Ministry of Defence would like to stress that the plane was over the Syrian territory throughout the flight."
Updating MPs on the incident, Mr Hammond chose his words carefully, saying that the jet was shot down "near the Turkish-Syrian border".
He said: "We are seeking further details urgently, both in Moscow and in Ankara. Clearly this is potentially a serious incident, but it wouldn't be wise to comment any further until we have got more certainty on the facts."
Video footage of the incident showed a plane on fire before crashing on a hill and two crew members apparently ejecting.
One of the crew members was dead upon landing, according to a spokesman for the rebel group that found him.
Jahed Ahmad, of the 10th Brigade in the Coast, said the crew members tried to land with their parachutes in Syrian government-held areas after they ejected, but came under fire from members of his group.
He added that rebels shot one of the pilots, who landed dead on the ground. The fate of the second pilot was not immediately known.
The group released a video showing gunmen standing around a blond pilot who had bruises on his face and appeared dead.
A voice on the video is heard saying "a Russian pilot", while another says: "The 10th Division has captured a Russian pilot. God is greatest."
Turkey has already complained about Russian incursions into its skies and last month Nato condemned the "unacceptable violations of Turkish air space by Russian combat aircraft".
The incident comes as David Cameron prepares to set out the case for RAF air strikes in Syria.
The Prime Minister will set out a plan on Thursday to tackle Islamic State - also known as Isil, Isis or Daesh - in its Syrian stronghold.
He told the Commons on Monday that he would let MPs consider his proposals over the weekend before a debate and vote on British military involvement in Syria.
"I do not want anyone to feel that they are being bounced into a decision," he said. "I want this House to take the decision deliberately, but we should not take too long over it."