A senior police official said the fear of possible attack was raised after Justice M B Shah Commission's report was tabled in Parliament.
"There are several documents in the department which are quoted in the Shah Commission report. The security is given to ensure that no one tampers with the documents," police said.
The state government has already shifted crucial royalty challans and no objection certificates (NOC) of iron ore export to a secured location.
The platoon of India Reserve Batallion was deployed near the Mines Department.
"Never know what the mining mafia will do in desperation. We are in no mood to take any chance," a police official said.
Shah Commission, in its inquiry report, has indicted former Goa chief minister Digambar Kamat for not acting against "illegalities" in the state's mining sector.
