Fourteen crew members were pulled alive from the water soon after the rig was hit by a powerful storm and sank under strong winds and high waves 200 kilometers off the coast of Sakhalin Island.
But the remainder of the crew of 67 is feared dead in the icy waters of the Okhotsk Sea, where water temperatures hovered just above zero degrees Celsius when the rig sank within 20 minutes.
In a December 19 statement, the Federal River and Sea Agency said there were 14 confirmed dead thus far, revising downward from an earlier toll of 16.
The Emergency Situations Ministry has denied earlier reports that a makeshift raft carrying 15 passengers had been located, Interfax reported.
When it sank, the "Kolskaya" drilling rig, built in 1985, was being towed by a Neftegaz-55 tugboat and an icebreaker from the Kamchatka Peninsula to Sakhalin Island, despite forecasts of a fierce storm.
President Dmitry Medvedev has ordered investigators to establish why the rig was being transported in such dangerous conditions, while investigators already say there are grounds for a criminal investigation.
"The investigation is mainly looking at the following version of events: that there was a violation of safety protocol while the drilling rig was being towed; and that the weather conditions were not taken into account when it was under tow as there was a powerful storm near the vessels," Vladimir Markin, spokesman for the federal Investigative Committee, said in a statement on the committee's website.
Rescue efforts through the night were hampered by continuing strong winds and waves 5 meters high. The Neftegaz-55 tugboat took part in the rescue effort but had to return to shore when it sustained hull damage.
Russian Emergency Situations Ministry officer Taimuraz Kasayev told Russian television in Yuzhno-Sakhalinsk on December 18 that weather conditions in the area where the accident occurred were "difficult," with wind speeds around 15 meters per second.
Local media say that the sinking of the rig lands a blow to Russia's bid to increase offshore oil-and-gas exploration in the face of declining onshore production.
It also comes at the end of a year marred by transport disasters and at a sensitive political time as the authorities face heightened public discontent in the wake of fraud-tinted parliamentary elections on December 4.
The sinking of the "Kursk" submarine that killed over 100 in the Barents Sea in 2000 had powerful political ramifications at the very beginning of then-President Vladimir Putin's rule after the bungled state response.
But Aleksandr Morozov, a popular blogger and independent political analyst, says he expects little political fallout from the "Kolskaya" disaster.
The Kremlin said in a statement posted on the presidential website that "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."