BEIRUT — Turkish military aircraft shot down a Russian jet Tuesday after Turkey says it violated its airspace near the border with Syria, a major escalation in the Syrian conflict that could further strain relations between Russia and the West.

Russian officials confirmed that a Russian warplane had been shot down but claimed it had been flying over Syria and had not violated Turkish airspace.

The plane was likely shot down “due to shelling from the ground,” the Russian Ministry of Defense said.

The Russian Defense Ministry said the plane was one of more than three-dozen fixed-wing aircraft flying sorties in Syria as part of Russia’s two-month old bombing campaign there. It is the first Russian plane to crash in that time.

The incident highlights heightened friction in Syria’s increasingly crowded airspace, which now includes Russian warplanes that are targeting the armed opposition of President Bashar al-Assad’s embattled forces.

It will almost certainly further strain relations between Russia and the West since Turkey is a member of NATO.

The Russian jet was warned several times before it was hit, Turkey’s military said, according to several news agencies.

The plane was flying at an altitude of 6,000 meters,” the Defense ministry added. “The fate of the pilots is being found out. According to preliminary information, the pilots ejected from the aircraft.”

Citing unnamed military sources, Turkey’s Dogan News agency reported the aircraft was downed because of a “border breach.” The news outlet said local witnesses observed pilots parachuting from the attacked warplane.

Relations between Turkey and Russia have soured over the Russian intervention. Turkey, which backs rebels seeking Assad’s ouster, has at least twice warned Russia about incursions into Turkish airspace.

In addition to Russia, Syrian warplanes and aircraft from a U.S.-led coalition are mounting separate air bombardments across the war-torn country.

Last month, Turkey’s military downed an unmanned aerial vehicle near the border with Syria that military analysts said appeared to be of a Russian make. Officials in Moscow denied connection to that downed aircraft and sent a delegation to Turkey to smooth over concerns.

Russia issued a formal apology to Turkey in early October when a jet violated Turkish airspace and Turkish F-16s were scrambled to intercept the plane. The Russians called the mistake “a navigational error.”

Russia has carried out more than 4,000 airstrikes since it began its intervention in the Syrian civil war on Sep. 30, using a force of modern and modified Soviet-era aircraft. Russia has at least 32 fixed wing aircraft and 16 helicopters at the Khmeimim Air Base near Latakia, Syria, an Assad stronghold on the Mediterranean Sea just 30 miles from the Turkish border.

The Russian deployment includes 12 Soviet-era Su-24 and 12 Su-25 ground support aircraft, as well as four cutting-edge Su-34 strike fighters. The Russians have also deployed four Su-30 fighter jets, which are used for air-to-air combat.

Following the bombing of a Russian charter jet in Egypt last month that killed all 224 people on board, Russia strategic bombers also began flying sorties against targets in Syria from bases on Russian territory. The planes include six Tu-95 turboprop strategic bombers and five Tu-160 strategic bombers, which must traverse Iraqi and Iranian airspace in order to reach targets in Syria.

Daniela Deane contributed from London.