A Yemeni security official says 12 Islamist suspects have been arrested in connection with an attack that killed four South Korean tourists at a historical site.

The official says those arrested are members of jihadi groups believed to have information on the actual perpetrators of Sunday's bombing. He spoke on condition of anonymity Monday because he wasn't authorized to talk to the media.

Discrepancies remain about the bombing that killed the South Koreans and their Yemeni guard near the ancient fortress city of Shibam.

An Interior Ministry statement says a roadside bomb was behind the attack.

The security official says a suicide bomber attacked the tourists. He says human remains believed to belong to the bomber were found.