A huge search operation is continuing "round the clock" in Russia, after a Russian military plane with 92 people on board crashed into the Black Sea.

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

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

All those on board are feared dead after Sunday's crash. Monday has been declared a national day of mourning.

Search teams – including 139 divers – worked through the night in three shifts, and the operation "did not stop for a minute", Defence Ministry spokesman Maj Gen Igor Konashenkov said at a briefing on Monday morning.

He said that 11 bodies and "154 fragments" have been found since the operation began.

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

The 10.5 sq km (four square miles) search area just off the coast had been extended, the spokesman said.

"Fragments of the Tu-154 plane of the Russian defence ministry were found 1.5km (one mile) from the Black Sea coast of the city of Sochi at a depth of 50m to 70m (165-230ft)," the defence ministry said on Saturday.

BBC