Russian law enforcement personnel armed with automatic weapons swept through IBM's offices in Moscow Wednesday morning, seizing documents as they went, according to sources familiar with the operation.

The motive for the raid was not immediately clear. A spokesman for IBM said the company is "cooperating with the authorities" but declined further comment.

A blogger who works at the office said the raid was carried out by the OMON special forces unit attached to Russia's Ministry of Internal Affairs. "Masked people with machine guns are wandering around the office ... they told us to leave our belongings and cell phones there and leave the room," the blogger wrote.

The blogger's comments appeared Wednesday in a report on a Web site operated by Moscow-based news agency Regnum.

A local source in Moscow who was present during the raid told InformationWeek by telephone that some of the personnel were armed "but no one was forced to lie on the ground or anything like that."

According to another blogger quoted by Regnum, the offices of local IBM technology partners LANIT and R-Style were also raided. The Russian news agency Novosti is reporting that IBM's office in central Moscow has been closed since Tuesday.

A source told InformationWeek that the office re-opened Wednesday afternoon, local time.