Saudi Arabian security forces on Saturday said they had killed Abdul Aziz al-Muqrin, the self-proclaimed leader of the Al-Qaeda in the kingdom.

Al-Muqrin had claimed responsibility for the beheading of US engineer Paul Johnson Jr on Friday.

The four were shot dead in Riyadh on Friday night, shortly after the "Al-Qaeda in the Arabian peninsula" posted photos on Web sites showing the beheading of the American, the interior ministry said.

They "were besieged in a gas station in the Al-Malaz district in Riyadh by security forces, and a heavy exchange of fire" ensued, said an interior ministry statement read on state television.

Photos of the bloodied bodies of Al-Muqrin and the others were shown on television.

The footage came after a statement in the name of the Al-Qaeda was posted on an Islamic Web site denying that Al-Muqrin had been killed.