From Alla Eshchenko and Maxim Tkachenko, CNN

December 19, 2011

Moscow (CNN) -- Rescue workers have found a raft with up to 15 people aboard near an offshore Russian drilling rig that capsized in the Sea of Okhotsk -- but it was unclear if they were alive, officials said Monday.

"Aircraft have found a rescue raft. Up to 15 people may be aboard; it is unknown whether they are alive or not," Yuri Melikhov, general director of rig owner JSC AMNGR, told reporters.

The rig capsized during a storm Sunday as it was being towed from Kamchatka. There were 67 people aboard the Kolskaya platform, which was subcontracted to a company working for the Russian energy giant Gazprom, state news agency RIA-Novosti reported.

By Monday, the death toll had reached 16 after authorities found more bodies in the freezing water. Fourteen others were rescued.

Authorities said the rig was floating about 200 kilometers (124 miles) from Sakhalin Island -- north of Japan and northeast of China.

It was drilling a well about 3,500 meters (11,480 feet) deep, RIA-Novosti said.

Taimuraz Kasayev, a spokesman for the regional emergencies service, told RIA-Novosti on Sunday the accident poses no environmental danger because the rig's fuel stocks were hermetically sealed and would not spill.

The television channel Russia Today reported that the rig was being towed into position when pumps failed, causing it to take on water and sink.