"A patrol car caught fire after it was hit by a bullet while chasing a suspects' car, which led to the martyrdom of three security men," the security source said on Sunday. 

Seven suspects were later arrested when security forces combed southern neighbourhoods of the town of Buraidah, located 340 kms northwest of Riyadh, he added.

Saudi security forces have repeatedly clashed with anti-government fighters blamed for a wave of violence in the desert kingdom since May 2003.

Some 90 people have been killed and hundreds wounded in the spate of bombings and shootings in Saudi Arabia - much of it directed at Westerners - over the past 16 months.