Russian researchers say they've obtained the first sample of transparent ice from the water of a unique sub-glacial lake in Antarctica.

The scientists have drilled into Lake Vostok, sealed for the last 20 million years beneath Antarctica's ice sheet at a depth of 2.3 miles, RIA Novosti reported Thursday.

Vostok, the largest of Antarctica's buried network of icebound lakes, may reveal new forms of life and show how life evolved before the ice age, the scientists said.

"The first core of transparent lake ice, 2 meters (6.5 feet) long, was obtained on January 10 at a depth of 3,406 meters (11,100 feet)," Russia's Arctic and Antarctic Research Institute said in a statement.

"Inside it was a vertical channel filled with white bubble-rich ice," it said.

The composition of the new core is being determined, because ice from Lake Vostok may have special physical properties different from those of ordinary ice, Vyacheslav Martyanov, the head of the Russian Antarctic Expedition's logistics center, said.