Molotov cocktails have been thrown at a building housing a regional branch of the Belarusian security service (KGB).
Nobody was hurt in the attack, carried out by a group of people. The building, in the city of Bobruisk, did not catch fire.
Police say hooligans are probably behind the arson attempt and that it may be linked to an earlier attack in Minsk.
On August 31, several Molotov cocktails were thrown in the grounds of the Russian embassy in the Belarusian capital. One hit a car parked near the building.
An anarchist group claimed responsibility on the Internet. However, so far nobody has been charged.