The black box recovered from the wreckage of a Russian military jet is believed to be in good condition.

The device, which contains information that could help identify the cause of Sunday's crash, is the first flight data recorder to be recovered from the Tu-154 jet, which came down two minutes after taking off from Sochi airport.

The black box will be sent to Moscow for analysis, a defence ministry official told TASS news agency.

According to the Interfax news agency, a second black box has been found in the wreckage but not yet raised to the surface.

It has also been reported by Russian media that the model of plane have been grounded, but those reports have yet to be officially confirmed.

All 84 passengers and eight crew members were killed in the crash, including dozens of singers in Russia's world-famous military choir who were on their way to Syria to entertain troops.

Russia's federal security service said it had "no signs or facts" to suggest the crash was an act of terror.

Andrew Roth, Moscow Correspondent with The Washington Post, says everything should become clearer once the flight recorders are examined.

"There is some reporting being put out there that the boxes are in good condition and can be decoded rather quickly," he explained.

"But that's based on source report [...] So we're going to have to wait-and-see exactly what does happen."

An investigation is focusing on pilot error, a technical fault, bad fuel and a foreign object in the engine as four possible causes.

The Russian defence ministry said the plane that crashed was built in 1983 and underwent factory check-ups and maintenance in 2014.

Search and rescue teams have recovered 12 bodies and 156 body fragments, it added.

On Monday, rescue workers recovered the plane's fuselage and brought it to shore.

Fragments of the jet were found 27 metres underwater, including "two elements of the plane's control mechanism".

More than 3,000 people and 27 ships have been involved in the search operation.