The Far East Amur Region Interior Affairs Department said the fossil tusks were discovered in the neighboring Republic of Yakutia.
The department said three men were planning to sell the tusks to Chinese nationals, the Russian news agency RIA Novosti reported.
Police were investigating whether the tusks were obtained legally.
One kilogram (2.2 pounds) is worth 5,000 rubles ($166) at international auctions, RIA Novosti said. Yakutia is the prime location for finding mammoth tusks, accounting for about 90 percent of the remains found.