Russian Mir submersibles will dive near the Baikal pulp mill to search traces of possible pollution, the head of the Baikal conservation fund said on Thursday.

Built in 1996, the Baikal Pulp and Paper Mill has long been under heavy criticism for being the largest source of environmental pollution of the world's largest freshwater lake. The issue came into spotlight again early this year after Prime Minister Vladimir Putin signed a resolution paving the way to the resumption of production in the protected area.

"On a request from [Russia's environmental regulator] Rosprirodnadzor, Mir mini-subs will perform dives near the Baikal Pulp and Paper Mill on July 12 to take samples," said Mikahil Slipenchuk, who also heads major investment group IFC Metropol which sponsored Mir dives in 2008-2009.

This year's mini-sub research of the world's largest and deepest freshwater lake will start later on Thursday, and will continue until September 5.

Listed as a UNESCO World Heritage Site, Lake Baikal is known for its natural beauty and biodiversity. Over 80% of the animals living in the lake are unique.

Russian environmentalists managed to amass 45,000 signatures in an appeal to stop further pollution of the lake by the mill, which had been suspended more than a year ago due to ecological concerns.

A public campaign to close or convert the Baikal Pulp and Paper Mill became a symbol of Glasnost, the policy of "openness" policy followed by Soviet leader Mikhail Gorbachev in the late 1980s.

The collapse of the Soviet Union in 1991 delayed the decision, and it was only in October 2008 that the plant switched over to a closed water cycle, preventing the discharge of waste into the lake.

IRKUTSK, July 1 (RIA Novosti)