The entrance of a Saudi religious police building has been set on fire, in a rare attack on a force criticised by the public for its heavy-handed tactics.

Formally known as the Committee for the Promotion of Virtue and the Prevention of Vice, religious police officers patrol the streets to enforce gender segregation and ensure the public behave in accordance with their strict interpretation of Islamic teachings.

Officers have power of arrest and the force has drawn public criticism in the past over car chases that have led to fatal accidents, prompting the committee's head to ban such pursuits.

Committee officials declined to comment by telephone, but a newspaper website quoted a spokesman as confirming the attack, which occurred at dawn on Saturday.

"The committee's branch in Thuhrat Al Badeia (West of Riyadh) was intentionally set on fire by assailants," Abdul Rahman Al Sheri, a committee spokesman, was reported as saying.