RIYADH (Reuters) – Saudi Arabia has arrested 17 suspected Islamic State sympathisers accused of plotting attacks on religious officials, security forces, civilian districts and economic and military targets, the interior ministry said on Monday.

Fourteen of those arrested are Saudi nationals, including one woman, ministry spokesman Mansour al-Turki told state television news channel Ekhbariya, which broadcast photographs of the accused.

The other three detainees were Yemeni, Egyptian and Palestinian, he said.

“The activities of this network went beyond the kingdom’s borders to provide technical and media support for Daesh,” said Turki, using an Arabic acronym for the Iraq and Syria-based Islamist militant group.

The cells had planned attacks on targets including the Shi’ite Imam al-Rida mosque in the eastern Saudi city of al-Ahsa, a public security training facility in Riyadh and an oil pipeline west of the capital city, said Turki.

They also conspired to plant an explosive device on the car of an employee of the Ministry of Defence in Riyadh.

The arrests followed months of investigation into the network, Turki said, adding that the militants had prepared more than 25,000 kg of adhesive bombs and explosive belts.

Authorities also seized pipe bombs, firearms, silencers and cash in excess of 600,000 riyals ($160,000).

Local Saudi affiliates of the Islamic State group have carried out several deadly shootings and bombings in the conservative kingdom, many targeting security personnel and Shi’ite mosques.

Islamic State is bitterly hostile to the Gulf Arab monarchies and is seen to be trying to stoke Sunni-Shi’ite sectarian confrontation in Arabian peninsula states to destabilise and ultimately overthrow them.

(Reporting by Katie Paul and Omar Fahmy, Editing by William Maclean and Gareth Jones)