An oil drilling rig with 67 crew on board capsized and sank off the Russian far eastern island of Sakhalin on Sunday when it ran into a storm while being towed, leaving 49 of the crew unaccounted for, the regional Emergencies Ministry said.
Fourteen crew members were rescued alive from the 'Kolskaya' jack-up rig, operated by Russian offshore exploration company Arktikmorneftegazrazvedka (AMNGR), and four bodies were recovered. The rest of the crew were missing.
The floating drilling rig capsized 200 kilometers (125 miles) off the coast of Sakhalin island at 12.45 local time (0145 GMT), the Emergencies Ministry said in a statement on its website.
The statement said a rescue craft and helicopters had been sent to the site to scour the waters for survivors.
President Dmitry Medvedev ordered all necessary help be allocated to the search and rescue of any remaining survivors in the icy waters, while the Emergencies Ministry said it would work through the night.
The disaster posed no ecological danger, but it will deal a blow to efforts by Russia, the world's largest energy producer, to step up offshore oil and gas exploration to offset a long-term production decline in onshore production.
There is no ecological danger. The vessel was carrying the minimum amount of fuel as it was being tugged by two craft, said a spokesman for AMNGR, a unit of state-owned Zarubezhneft.
The 'Neftegaz-55' tugboat, also owned by AMNGR, had been towing the Kolskaya rig and took part in the search effort, but pulled out after suffering hull damage. The tug, carrying 11 crew rescued from the rig, was limping to port.
An icebreaker, the 'Magadan', was still at the scene.
Most of the missing crew were from the far eastern town of Magadan, AMNGR said. The company, based in the northern port of Murmansk, flew out counsellors to support relatives.
He said a company commission was working out the financial losses from the lost drilling vessel.
RIG WAS WORKING FOR GAZPROM
The rig, built in Finland in 1985, had been doing work on a minor gas production project in the Sea of Okhotsk for a unit of state-controlled gas export monopoly Gazprom, the company said.
The Kolskaya was heading to the port city of Kholmsk on the western side of Sakhalin island from the Kamchatka peninsula when strong winds and high waves capsized the vessel. It sank in 20 minutes into waters that are more than 1,000 metres deep.
(President) Dmitry Medvedev has ordered all necessary assistance be provided to the victims of the drilling platform accident and has ordered a probe into the circumstances of the loss of the platform, the Kremlin said.
Russia's prize offshore gas and oil fields lie to the northeast of Sakhalin island.
Two major offshore projects are already producing oil and gas off Sakhalin - Sakhalin-1, operated by Exxonmobil and Sakhalin-2, in which Gazprom has a controlling stake.
The disaster is unlikely to seriously affect oil or gas production. AMNGR said the vessel was no longer under contract when it sank.
Operating conditions at the Sakhalin fields, explored by Soviet geologists in the 1960s and 1970s, are among the harshest for Russian energy companies.
The jack-up rig, which has three support legs that can be extended to the ocean floor while its hull floats on the surface, was overturned in stormy winter conditions with a swell 5-6 metres high.
The violation of safety rules during the towing of the drilling rig, as well as towing without consideration of the weather conditions ... are believed to be the cause of the (disaster), investigators said in a statement on their website.
Winter often lasts 220-240 days in the waters off Sakhalin, where the main companies operating are ExxonMobil, Gazprom, and Royal Dutch Shell, who produce oil and gas, sometimes in icebound conditions, for export largely to Asian markets.
Sakhalin-2, in which Shell and Mitsui also have stakes, produces 10 million tonnes per year of liquefied natural gas at Russia's only LNG plant in the port of Prigorodnoye for export to Asia, much of it to Japan.
Each tanker of crude oil produced by at the 160,000 barrels-per-day Sakhalin-1 project, operated by ExxonMobil, is escorted by two icebreakers when ice thickness reaches 60 centimetres.
State-controlled Rosneft this year reached a major deal with Exxon to explore for oil and gas in the Kara Sea, to the north of the Russian mainland, a largely unexplored region estimated to hold over 100 billion barrels of oil.
A combination of poor infrastructure and chronic corner cutting has dealt the country its share of sea disasters, notably the 2000 sinking of the nuclear submarine Kursk in the Barents Sea in August 2000, killing all 118 aboard and prompting criticism of the sluggish response.
(Additional reporting/editing by Douglas Busvine)