The Kremlin said the investigation into the crash was continuing and it would be inappropriate to comment before the official conclusion. Kremlin spokesman Dmitry Peskov said: "It is wrong to speculate before the conclusion of the investigation."

Earlier on December 25, flight J2-8243 crashed near the city of Aktau, Kazakhstan after changing course away from southern Russia, an area where Moscow has repeatedly used its air defense system against Ukrainian drone attacks.

The Embraer plane, which had departed from the Azerbaijani capital Baku and was headed to Grozny in Chechnya, veered hundreds of miles off course over the Caspian Sea. Officials did not explain why the plane flew over the Caspian Sea. The nearest Russian airport on the flight route, Makhachkala, was closed on the morning of December 25.

Russia's civil aviation agency, Rosaviatsia, said the pilots diverted to Aktau after hitting a bird, leading to an emergency on board.

According to four sources familiar with the Azerbaijani investigation, the plane was shot down by a Russian air defense system. One source said preliminary results indicated that the plane was hit by a Russian Pantsir-S air defense system and that its communications systems were paralyzed by electronic warfare equipment as it approached Grozny.

Mark Zee, an expert from OPSGroup, a unit that monitors airspace and airport risks around the world, said that the possibility of the plane being hit by a surface-to-air missile (SAM) is very high, about 90-99%. Osprey Flight Solutions, a British aviation security company, also warned that the possibility of the plane being shot down by a Russian military air defense system.

Kazakhstan's Deputy Prime Minister Qanat Bozymbaev said he could neither confirm nor deny the theory that Russian air defenses shot down the plane. Kazakhstan's transport prosecutor at the crash site said the investigation had not yet reached a definitive conclusion.

At a press conference on December 25, Azerbaijani President Ilham Aliyev said it was too early to speculate on the cause of the accident, but confirmed that the plane had to change course due to bad weather conditions.

"The information I received is that the plane changed its route from Baku to Grozny and headed towards Aktau airport, where it crashed while landing," he said.

Images from the scene show the tail of the plane may have been damaged by missile debris.

ADS-B flight tracking data shows that the Azerbaijani plane was jammed by GPS as it flew over southwestern Russia. Russia has previously used electronic jammers to distort the location of drones and Ukrainian communications systems.

Hoai Phuong (according to NDT, Reuters)