Investigators enter the submarine for half an hour and they need another half an hour to recover

Vladimir Ustinov

Three bodies were removed on Thursday, when investigators entered the wreck for the first time, and a further nine were recovered on Friday.

"Exactly how many of our heroes we'll manage to get out of the vessel is still hard to say," the Russian prosecutor-general, Vladimir Ustinov said.

Mr Ustinov has said it may take more than a month to identify the bodies, which spent more than a year on the bottom of the Barents Sea after two explosions sank the submarine in August 2000.

However, on Friday they said the bodies were better preserved than expected.

The Interfax news agency says that one has already been identified as Aleksey Stankevich, a medical service captain.

Investigators are hurrying to retrieve any bodies they can find before they deteriorate through contact with air.

"Sea water preserved the bodies, but as there is no water now, the bodies are subject to changes and experts have to work fast," Mr Ustinov said.

"Investigators enter the submarine for half an hour and they need another half an hour to recover from what they saw inside."

Body count

The vessel was raised from the sea bed in a hazardous operation that climaxed earlier this month.

Russian TV showed a close up of the damaged hull

It was placed in dry dock at the weekend.

On Friday officials said they had succeeded in opening an internal lock and reaching the section of the submarine containing its reactors.

They said the next step would be to enter the section, cut all cables, and weld closed all openings.

At least 23 of the 118 sailors on board are known to have survived the blast, taking refuge in the submarine's sternmost section.

Twelve bodies were recovered by divers in the weeks following the explosion last year.

Click here to see a graphic of the inside of the Kursk

Forensic tests on the bodies recovered this week are said to have begun already.

Experts say that the force of the blasts which sank the submarine could mean that most of the crew were simply vaporised.

After all the bodies are recovered, work will start inspecting equipment and documents.

Poisonous gases

The investigation team includes chemical, biological and radiation experts from the Northern Fleet.

The navy says radiation levels remain normal

They are wearing oxygen masks and are cloaked in heavy suits to protect them from poisonous gases and possible radiation - though officials said radiation levels remained normal.

The Russian authorities are keen to determine the cause of the explosions, which is still unknown.

Theories include an accident with a faulty torpedo and a collision with another submarine or old anti-shipping mine.

Russia rejected again this week a theory that the submarine was hit by a missile fired from a ship taking part in naval exercises with the Kursk at the time of the disaster.

Mr Ustinov has said the bow section of the submarine, which was too fragile to be lifted to the surface with the rest of the wreck, will hold the best information about what caused the sinking. That is due to be lifted next year.

Preparations are also under way for the removal of the Kursk's 22 Granit cruise missiles - each of which has a 1,000 kilogram warhead and weighs 6.9 tonnes.

A spokesman for the Northern Fleet said it appeared the missile silos had not been damaged, and that they could therefore be removed without cutting through the hull.