VimpelCom (VIP) plunged 21% after the Russian telco said it could owe up to $157 million in back taxes and penalties.

The Moscow-based company said those figures come from preliminary conclusions of a review of its 2001 tax filing. The company said the country's "tax inspectorate" views VimpelCom as owing an added 2.5 billion rubles in taxes and 1.9 billion rubles in fines and penalties.

"A large portion of this amount relates to the deductibility of expenses incurred by VimpelCom in connection with the agency relationship between VimpelCom and its wholly owned subsidiary, KB Impuls, which holds the GSM license for the city of Moscow and the Moscow region," the company said. VimpelCom added that the finding was preliminary "and is not a final tax claim or demand by the inspectorate."

The company said it doesn't agree, will respond in writing and expects to work the disagreement out.

VimpelCom fell $8.23 to $30.25.