Four people were dead and 49 missing after a drilling platform with 67 people on board overturned in the Sea of Okhotsk in Russia's Far East on Sunday, news agencies reported.

A TV frame, taken on Dec. 18, 2011, shows a local TV station's report on an overturned drilling platform, in the Sea of Okhotsk in Russia's Far East. Two people were dead and 51 missing after a drilling platform with 67 people on board overturned in the Sea of Okhotsk in Russia's Far East on Sunday, news agencies reported. (Xinhua/Li Yong)

All the rescued were in life-jackets and two empty life boats were found, Taimuraz Kasaye said.

There was no danger of a fuel spill because the oil rig contained only small amount of fuel "in sealed tanks," he added.

Two helicopters, an icebreaker and another ship are searching for those still missing. Officials did not say whether there was any hope of finding survivors.

Russian media reported that a distress signal was sent out while the platform Kolskoye was being towed by the Magadan icebreaker amid high waves and strong winds.

"In the process of towing, the gas pipes of the tanks were damaged and water started flowing inside of them. The rig's water discharge systems were operating at their maximum capacity," the Interfax said, quoting sources from the Russian Transport Ministry.

The platform overturned so quickly that the crew had no time to shift to inflatable life rafts, said the Itar-Tass news agency.

The rig tilted and sank within 20 minutes, a Transport Ministry official told the Interfax.

According to Sakhalin weathermen, there are strong winds and waves up to 4 meters high on the sea, which is hampering rescue efforts.

Kasaye said the search and rescue had to be suspended at night and will resume on Monday morning. But Russian Emergency Situations Ministry told media the rescue will not stop during night and the ministry was considering sending more helicopters to the scene.

Russian President Dmitry Medvedev had ordered assistance to the victims, said the Kremlin press service.

A criminal probe had been launched into the accident.

The Far Eastern Investigative Committee said violation of safety laws in the towing of the rig and the harsh weather condition might be the two key causes of the accident.

The rig, operated by Russian exploration company Arktikmorneftegazrazvedka (AMNGR), is about 200 km off Sakhalin Island. It was engaged in shelf exploration on the Okhotsk Sea.

The 69-meter-long and 80-meter-wide platform was built in 1985 in Finland, capable of carrying up to 102 people.

VietNamNet/Xinhuanet