Those who died had swigged a bath oil called Hawthorn whose label advertised an ethanol content of 93%.
President Vladimir Putin on Wednesday demanded restrictions on the sale of surrogate alcohol after at least 62 people died in Siberia from drinking bath oil laced with methylated spirit in search of alcoholic highs.
The mass poisoning in Irkutsk, a hard scrabble city around 2,600 miles (4,000 km) east of Moscow, is the worst of its kind in recent years and has prompted nationwide soul-searching and condemnation.
Putin asked ministers to draft tighter rules for the production and sale of drinks, perfumes and other liquids with more than 25 percent alcohol content as well as medicines containing ethanol.
Up to 12 million mostly poor Russians are estimated to use cheap surrogate spirits, many produced in illegal facilities, and a two-year economic slump has pushed more people into poverty.
Those who died in Irkutsk had swigged a bath oil called Hawthorn whose label advertised an ethanol content of 93 percent.
Investigators said bootleggers had been selling the product for a long time without any instances of poisoning, but that the fatal batch was contaminated by methylated spirit, a toxic substance found in cleaning materials and paint stripper.
Russia's top investigator Alexander Bastrykhin flew to Irkutsk this week to take charge of an operation that has searched more than 1,500 points of sale and confiscated 6,500 litres of sprits, according to the Investigative Committee.
"As of now, 12 people have been detained," the committee said in a statement on Wednesday.
The Irkutsk region's health ministry said on Wednesday that the number of deaths from the poisoning had risen to 62 from 41 on Monday, and that 36 people remained in hospital.
(Reporting by Peter Hobson; Editing by Andrew Osborn)
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