All 92 people on board a Russian military passenger plane are believed to have died after it crashed into the Black Sea en route to Syria on Sunday, according to media reports.

The 33-year-old Tu-154 jet, which had been serviced recently, was carrying soldiers, reporters and 64 members of the Red Army Choir who were to perform for Russian troops.

Debris and 11 bodies have been found, with no reports of survivors, said a BBC report.

The plane disappeared from radar two minutes after taking off from Sochi at 05:25 (02:25 GMT), heading for Latakia in Syria, the Black Sea resort where the plane had made a refuelling stop, the defence ministry said.

As of Sunday evening, the cause of the plane crash had yet to be determined. Though officials were saying terrorism was not seen as the likely cause, Russia’s special Investigative Committee, which opened a criminal inquiry, was considering all possibilities, according to a Washington Post report.

“Of course, the entire spectrum and almost any possible causes.?.?. are being probed, but it is premature now to speak about this” as a terrorist act, Transport Minister Maxim Sokolov told reporters in Sochi.

Maj Gen Igor Konashenkov, a military spokesman, told reporters in Moscow that no one survived after the aging Soviet-era jet, which had set out from Moscow.

The plane had not sent a distress signal. The pilot was “first class,” Konashenkov said.

In nationally televised comments, Russian President Vladimir Putin declared Monday a national day of mourning and said the cause of the crash would be carefully investigated.