It is not yet clear whether Russian scientists have succeeded in their quest to drill into Lake Vostok.
National media on Monday reported a breakthrough into the lake, the largest of more than 300 bodies of liquid water buried under Antarctica's ice.
But Valery Lukin, the Russian Antarctic programme director, has told Nature journal that the claim is premature.
He said data from a number of sensors monitoring the drilling had yet to be analysed.
"Only when I will have this I can say we penetrated [the lake]," Nature quoted him as saying. "We want to be sure we have really reached the surface of Lake Vostok."
Russian, British and US researchers are in a race to see who will be first to reach down into the waters of an Antarctic subglacial lake.
These bodies of water have been sealed off from the atmosphere for millions of years and so may contain life forms new to science.
The Russians have been leading the way with their drilling project in the east of the White Continent. Read More