The Saudi government alleged that Saudi recruits of a radical Islamist group in Syria plotted with others inside the kingdom to assassinate leading religious figures and security officials.

The alleged plot, and another involving al Qaeda's Yemen branch, were behind the arrests of 62 terror suspects in Saudi Arabia. Those arrested included 35 previously convicted Saudis, some of them graduates of the kingdom's rehabilitation program for militants, Interior Ministry spokesman Maj. Gen. Mansour al Turki said on Sunday. Saudi officials haven't said when they were arrested.

Until now, the rebel group Islamic State of Iraq and al-Sham (ISIS) was believed to have confined its activities largely to Syria and Iraq. If the allegations are true, this would mark the first known attempt by ISIS to plan an attack in the kingdom.

"This organization that we followed actually is very much related to Da'esh and was taking orders from Da'esh" in Syria, Maj. Gen. al-Turki said in a telephone interview, using an Arabic acronym for ISIS.

The Saudi ISIS recruits reached out to allies inside the kingdom to "push these people to start working and spotting such high-profile people" for assassination, he said.