Saudi Arabia has broken up four ISIS cells suspected of providing shelter and financial support to wanted militants and recruiting fighters, spokesman of the Saudi Interior Ministry Maj. Gen. Mansour al-Turki said on Thursday.

Maj. Gen. al-Turki said in a statement that security authorities have arrested 18 suspects belonging to the ISIS terrorist group in the holy cities of Mecca and Medina and two other cities. He added that the terror suspects had experience in making explosives and suicide vests.

According to the statement, automatic weapons were seized from the four cells, which comprised 15 Saudis, two Yemenis and a Sudanese man. Security forces also seized more than two million riyals (£426,700) in cash.

Among those helped to hide by the cells, which operated in the capital Riyadh and in eastern and northern regions, was Taye’ al-Say’ari, one of two suspected Islamist militants killed in a security operation in Riyadh last month.

“Cell members were (also) active in … choosing and conducting surveillance of targets and passing information to the organization abroad, promoting the deviant group and recruiting members for the organization and inciting them to fight in areas of struggle,” the statement said.

Maj. Gen. Turki said that Saudi Arabia has been targeted by a number of deadly suicide bombings and other attacks claimed by the ISIS group in recent years. The Kingdom is part of the U.S.-led coalition fighting the group in Iraq and Syria. Saudi Arabia says it has arrested hundreds of ISIS members.