Russia has found the main flight recorder from a military plane that crashed into the Black Sea killing all 92 on board, the Russian Defence Ministry said, amid unconfirmed reports that authorities had grounded all aircraft of the same type.
The recorder, one of several reported to be on board, contains information that could help investigators identify the cause of the Christmas Day crash, which killed dozens of Red Army Choir singers and dancers en route to Syria to entertain Russian troops in the run-up to the New Year.
Investigators have so far said that pilot error or a technical fault, rather than terrorism, are most likely to have caused the Tupolev-154 to crash into the sea.
The black box, which was found by a remote-controlled underwater vehicle at a depth of around 17 metres (55ft) near the resort of Sochi, has been sent to a defence ministry facility in Moscow for analysis.
"After it is technically cleaned in distilled water we will start transcribing it."
The ministry said numerous fragments of the plane had been found, including the engine, the landing gear and pieces of the fuselage.
The Interfax news agency cited an unnamed source as saying Russia had grounded all TU-154 planes until the cause of the crash became clear. However, there was no official confirmation of that.
The defence ministry said the downed jet, a Soviet-era plane built in 1983, had last been serviced in September and underwent more major repairs in December 2014.
Russian pilots said the TU-154 model is still flight worthy, though major Russian commercial airlines have long since replaced it with Western-built planes.
Experts said only two are registered with Russian passenger airlines with the rest registered to various government ministries.
The last big TU-154 crash was in 2010 when a Polish jet carrying then-president Lech Kaczynski and much of Poland's political elite went down in western Russia killing everyone on board.
The Interfax news agency, citing a law enforcement source, said a second flight recorder had also been found in the wreckage of the crash, but not yet raised to the surface.
The defence ministry said that search and rescue teams have so far recovered 12 bodies and 156 body parts.