Saudi Arabian security forces have arrested 42 suspected terrorists including four foreign nationals for involvement in earlier attacks across the kingdom, the Interior Ministry said in a statement Saturday. On Friday, Saudi security forces killed six suspected al-Qaida members and arrested a seventh following an exchange of gunfire in the capital Riyadh. One policeman was killed in the clashes. Saudi Arabia launched an aggressive anti-terrorism campaign in May 2003 after suicide bombers linked to al-Qaida attacked three residential compounds in the capital, Riyadh. Hundreds have been detained in the campaign, which has managed to capture or kill most of those named on its two most-wanted lists. Saturday's statement said that 27 of the detainees, including an Ethiopian and two Somalis, were rounded up during May 9-23 in Riyadh, Mecca, the Eastern Region province, and the province of Hafr al-Baten that borders Iraq. All 42 are part of a group that is inspired by "takfiri doctrine" under which those who don't adhere to its particular fundamentalist vision of Islam are considered "infidels." Security detained an Iraqi and three Saudis June 17 in raid on desert camp in Hafer al-Baten. The remaining nine - all Saudis - were captured at a "hideout in the desert in (the eastern province of) Hafr al-Baten on the Iraqi borders," an official told The Associated Press on customary condition of anonymity without saying when the arrests occurred. Another two were arrested since Friday's raid. The statement gave the names of those killed in Friday's raid - all suspected members of al-Qaida. None were on the latest most-wanted list issued by the kingdom in June 2005.