MOSCOW -- Russian scientists leading a submarine expedition to probe the world's deepest lake on Thursday carried out test dives ahead of the start of the operation next week, reports said.

The trial runs at Lake Baikal lasted two hours with two submarines diving to a depth of around 420 meters (1,386 feet), the Russian media reports quoted the organizers as saying.

On Tuesday, the expedition will begin in earnest with the submarines attempting to descend 1,637 meters (5,402 feet) to the bottom of the lake which has a unique ecosystem and has never been explored.

The expedition is being organized by Artur Chilingarov, a pro-Kremlin member of parliament and an Arctic explorer who led the team of scientists that planted a flag at the bottom of the North Pole in August last year.

Previous missions have only descended hundreds of meters.

Scientists will collect samples at different depths and hope to document the effects of global warming on the lake, as well as drawing the attention of the Russian government to the need for greater environmental protection.

The mission at Lake Baikal -- a UN World Heritage site which contains around a fifth of the world's freshwater reserves -- will carry out dozens of dives by the Mir-1 and Mir-2 mini-submarines.