The interior ministry said police in the southern city of Taganrog had been alerted that 1 million rubles ($13,600) worth of equipment had been stolen from an Ilyushin Il-80 plane at an airfield.

President Vladimir Putin's spokesman Dmitry Peskov described the breach as an "emergency situation" and vowed that "measures will be taken to prevent this from happening in the future."

The interior ministry did not specify what was stolen but said that investigators had been dispatched to the scene.

The port city of Taganrog, more than 1,100 kilometres south of Moscow, is home to Beriev Aircraft Company, a struggling state-controlled enterprise.

Both the interior ministry and Beriev declined to comment when reached by AFP.

But the Kremlin-friendly REN-TV television channel reported earlier this week that radio equipment was taken from an Il-80 plane that was undergoing maintenance at Taganrog.

Thieves opened the aircraft's cargo hatch and shoe and fingerprints were found inside the plane, the channel said adding that Beriev reported the theft to police last week.

The channel said that 12 people had been questioned as part of the probe that was made public on Wednesday.

Citing a source, it said officials with access to the airfield could be behind the high-profile theft.

The robbed plane is one of four highly-classified flying command centres built to evacuate the president and other top officials in case of a nuclear explosion.

Almost windowless, the first such Russian plane is believed to have flown in 1985.