The second stage of a major expedition to explore the depths of the lake began on August 20.
Arnold Tulokhonov, director of the Baikal Institute of Nature Management at the Russian Academy of Sciences, said: "The new oil fissures were discovered along the east coast of Lake Baikal, at a depth of around 600 meters (1,970 feet)."
He said that during the ongoing expedition, the Mir-1 and Mir-2 mini-submarines have enabled scientists to take samples of the oil at source for the first time.
During the current stage, set to run until the beginning of September, the mini-subs are exploring Talanka Bay near the mouth of the Selenga River on the southeastern shore.
An oil source was found during the first stage of the expedition, conducted from July 29 to August 18 in the deepest part of the lake.
Part of the ongoing research is focused on examining the processes through which microbes in the world's deepest lake digest petroleum that naturally enters the water.
Dr. Mikhail Grachyov, an expert on the molecular evolution of Baikal's animal and plant life, said earlier that the first oil source was found at a depth of around 850 meters (2,800 feet) to the south of Barguzin Bay, and that samples of the oil had been taken.
"It turns out that a large number of organisms live in this oil. This will require a huge amount of study," he said.
"We will study everything - the oil, the means through which it is broken down, the microbes, physical characteristics, and so on. This is necessary both for fundamental science and for practical goals."
He also said research into Baikal's oil may provide new insights into the origins of petroleum.
The consensus view among scientists is that crude oil is formed by decayed plant matter accumulating on the bed of a body of water and being subjected to heat and compression under heavy sediment over a period of millions of years.
However, several Russian scientists going back as far as Dmitry Mendeleyev have suggested an 'abiogenic hypothesis,' according to which petroleum was formed from carbon deposits originating deep in the Earth's mantle.
Baikal is the world's oldest lake, with an age estimated at 25 million years. Scientists taking part in the current expedition, during which 160 deepwater dives are planned over the next two years, have stressed that research is not aimed at exploiting possible oil and gas reserves, but at protecting Baikal's unique ecosystem.
The lake has been the focus of major environmental scares in recent years, with a last-minute change to an oil pipeline route that was set to pass near Baikal's shores, and environmental regulators' claims against a pulp mill accused of pumping large volumes of toxic waste into the lake.
Baikal, a UNESCO World Heritage site, holds around 20% of the planet's freshwater.
