SEOUL, South Korea -- Prosecutors raided the offices of Korea Railroad on Monday as part of a probe into a failed Russian oil deal in which the state-run agency lost millions of dollars, local media reported.

Last year, the railroad agency agreed to invest in an oil field project on Sakhalin Island and paid a deposit of $6.2 million on the deal to investment group Alfa Eco. The Russian government later denied approval for the project and the Koreans decided to withdraw from the contract.

Earlier this month, Alfa Eco said it would return only $2.7 million of the deposit, according to the terms of the agreed contract. The Board of Audit and Inspection of Korea last week said the railroad "incurred damage to the nation by jumping into the project without legal basis, survey of profitability, as well as appropriate internal decision-making process."