Russian search teams are continuing a huge operation in the Black Sea after a military plane with 92 people on board crashed on Christmas Day.

Some 3,500 people on ships, jets, helicopters and submersibles are involved in the operation near Sochi.

The Tupolev Tu-154 plane – carrying soldiers, members of famed Alexandrov army music ensemble and reporters – was heading for Syria.

All those on board are feared dead after yesterday’s crash.

Russian President Vladimir Putin has declared a national day of mourning on Monday, December 26.

At a briefing on December 26, Defense Ministry spokesman Maj. Gen. Igor Konashenkov said that search teams – including 139 divers – worked through the night in three shifts, and the operation “did not stop for a minute”.

Igor Konashenkov said that 11 bodies and “154 fragments” have been found since the operation began.

Image source WIkimedia

Overnight, he added, powerful spotlights were used to search the crash area.

The 4 square miles search area just off the coast had been extended, the spokesman said.

Ten of the bodies have already been sent back to Moscow for identification, media reports say.

On December 26, Russian Transport Minister Maksim Sokolov said that terrorism was not “among the main versions” of the possible causes of the crash.

He reiterated that investigators were looking into whether a pilot error or technical fault may have brought down the aircraft.

The minister earlier stressed that it was too early to speculate on possible crash causes.

Russian media quoted Aerospace Forces Commander Viktor Bondarev as saying that the plane’s black boxes had been located and they were not likely to have been damaged.

The aircraft disappeared from radar two minutes after taking off from Sochi’s Adler airport at 05:25AM local time, heading for Latakia in Syria, the defense ministry said.

The flight had originated in Moscow and landed in Sochi for refueling.

It was carrying 64 members of the famed Alexandrov Ensemble, who were to perform for Russian troops in Syria.

An audio recording played on Russian media and said to be of the final conversation between air traffic controllers and the plane reveals no sign of any difficulties.

Voices remain calm until the plane disappears and the controllers try in vain to re-establish contact.

The plane came into service in 1983.

Maj. Gen. Igor Konashenkov said the plane was last serviced in September and had undergone more substantial repairs in December 2014. It had an “experienced” pilot, he said.