The man, who suffered lacerations on both arms as well as fractured ribs, had driven to the taiga region on January 1 with his brother to celebrate the New Year.
"We are guessing that the victim may have provoked the attack himself, as these predators normally don't attack humans without cause," said Vitaly Starostin.
Starostin said that the victim was so drunk at the moment of the attack that could not remember the place where he had met the animal. Later he was only able to roughly point out two areas in the forest where the attack may have taken place. The spots were some 20 km (12 miles) apart.
Siberian tigers, also known as Amur tigers, are the world's largest subspecies of tigers. They are on the World Conservation Union's critically endangered status list, with about 500 of them left in the wild.
On December 25, 2007, a Siberian tiger named Tatiana escaped its enclosure in the San Francisco zoo, killing one person and injuring two before being shot dead.