The Iranian Revolutionary Guards arrested a member of Islamic State and foiled a plan for suicide attacks, a Guards commander said on Wednesday.

Col. Amin Yamini, the Guards commander for the western Tehran suburb of Shahriar, did not say when the arrest was made but said the attacks were being planned for a 10-day Shi’ite religious holiday that begins next week.

The Islamic State member arrested was from the Syrian branch of the militant Sunni organisation and had planned to organise about 300 people to carry out suicide attacks, Yamini said, according to Basij Press, the news site for the Tehran branch of the Guards.

On June 7, Islamic State attacked the parliament in Tehran and the mausoleum of Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic, south of the capital, killing 18 people and wounding more than 40.

Iran has blamed Saudi Arabia for being behind the deadly attacks. Riyadh has denied any involvement.

The Revolutionary Guards fired several missiles at Islamic State bases in Syria on June 18 in response to that attack.