The Kolskaya oil drilling rig sank off the island of Sakhalin in the Russian Far East on Sunday during a storm [REUTERS]

Russian rescue workers are continuing to search for dozens of people still missing more than a day after an oil rig capsized, but admitted that hopes of finding anyone else alive in the icy waters were fading fast.

The owners of the Kolskaya rig said on Monday that a raft with a possible 15 people onboard had been spotted, but a spokesperson for the emergencies ministry on the island of Sakhalin in the Russian Far East cast doubt on that claim.

Fourteen people were rescued from the water soon after Sunday's accident while authorities have confirmed that 16 bodies have been found. But 37 of 67 people on the rig when it capsized are still unaccounted for.

"Until all the people are found the rescue operation will not be concluded," Natalya Salkina, a spokeswoman for federal transport investigators in the city of Khabarovsk in Russia's Far East told Reuters.

Asked how likely it was that anyone would be found alive at sea in such icy temperatures, she said: "You can always hope for a miracle."

The jack-up oil rig, the Kolskaya, owned by state-owned offshore exploration firm Arktikmorneftegazrazvedka (AMNGR), was being towed from the Kamchatka peninsula across the sea towards Sakhalin Island when it capsized and sank in stormy weather on Sunday.

The Kolskaya platform – 70m long and 80m wide - was built in Finland in 1985. It had recently done some work for Russian energy giant Gazprom.

Russia produces most of its oil onshore and it hasn't seen any significant oil platform accidents in the past years.

Source: Agencies