Liberty Mutual, one of the largest insurance companies in the world, said it would enter the Russian market with a deal to acquire KIT Finance Insurance, which primarily writes auto coverage in St. Petersburg and Moscow.

Terms of the deal were not disclosed. Liberty Mutual is buying KIT from a holding company controlled by the state transport monopoly Russian Railways and its pension fund.

Boston-based Liberty Mutual, the world’s ninth-largest property and casualty insurer by revenue, gets just over a quarter of its net written premiums from international markets. Passenger auto is the largest line within that segment.

U.S.-based insurers have lately been pushing for international growth after years of weakness in domestic rates. Most have focused on Asia or Latin America, though, rather than the $21 billion Russian market.

KIT Finance has a small piece of that market, with about $50 million in written premiums last year, though Liberty said on Thursday it has been growing at a 27 percent annual rate