Two Saudi citizens were also detained by state security for their suspected involvement in the plot

Saudi Arabia has arrested several ISIS suspects it believes were plotting a suicide bombing attack on its defence ministry headquarters in the capital Riyadh, state news agency SPA quoted a security official as saying on Tuesday.The likely bombers were identified as two Yemeni nationals living under aliases in the kingdom who were detained along with two Saudi citizens also suspected of involvement in the plot, the official from the Presidency of State Security added.Saudi Arabia has previously been hit by deadly bombing and shooting attacks by ISIS targeting security forces and Shi'ite Muslims.The assailants were training in the use of explosive belts, the security source added, while authorities said they seized grenades and firearms during the operation to foil the attack.ISIS has for years criticized the leadership of Western-allied Saudi Arabia, the world's top oil exporter, accusing it of deviating from their strict interpretation of Islam and advancing the interests of their U.S. enemies.

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In a separate news item, SPA quoted a security source saying it had uncovered the "intelligence activities for the benefit of foreign parties of a group of people against the security, interests, principles, capabilities and social welfare of the kingdom in order to provoke sedition and harm national unity."The official did not elaborate and it was not immediately clear if the two cases were linked.