Riyadh: Saudi forces on Monday killed about five suspected militants believed to be linked to an Al Qaida attack on a major oil facility, security sources said.

A firefight ensued at dawn after security forces besieged the men, who were hiding in a villa in the affluent Al Hamra district of east Riyadh where several Western residential compounds are located.

Witnesses said they heard the sound of heavy gunfire and what appeared to be mortars as security forces surrounded the area and sealed it off before dawn.

The shoot-out ended after two hours with the deaths of all of the men inside the building, believed to number about five, the security sources said.

"The clashes in Riyadh have finished and all the suspects, who were barricaded in a house in the east of Riyadh, have been killed," the AlArabiya television channel reported.

According to its correspondent, five men were killed in the action.

A large quantity of arms were seized from their hideout.

One source said the men were traced partly through Internet surveillance. An Internet statement was issued at the weekend claiming that Al Qaida was behind an attack on the world's largest oil processing plant in Abqaiq on Friday.

Friday's attack on the oil facility is the first direct strike on a Saudi energy target since the militant group launched attacks aimed at toppling the monarchy in 2003.

It was also the first major attack by militants opposed to the Saudi monarchy since suicide bombers tried to storm the Interior Ministry in Riyadh in December 2004.

Authorities say two of the bombers were on a list of top wanted Al Qaida-linked Islamic militants issued last year.