At least half a million people took part in funeral processions for victims of last week's deadly terror attack on a Shia mosque in eastern Saudi Arabia, local media reported.

MANAMA (Sputnik) — Last Friday, the attack on the mosque in the village of Qadeeh, located in the Qatif governorate of the Eastern Province, killed 21 and injured over 100. The Saudi branch of the Islamic State claimed responsibility for the act. Saudi police have identified the suicide bomber who carried out the attack, a 20-year-old resident of the same village affiliated with ISIL.

The victims were buried following funeral prayers held in the Qadeeh market square on Monday, according to the Saudi Al Riyadh daily. The procession stretched for over three miles from different settlements in the province to the burial site, the publication said.

The biggest rally I ever saw in #Saudi,during the funeral of 20 Saudi Shia killed in IS suicide bombing last Friday pic.twitter.com/LZJGtLE2wU — Nasser Atta (@nasseratta5) 25 мая 2015

Security forces were patrolling all entrances to the square on Monday, searching everyone in attendance due to fears of new terrorist attacks during the funeral.

Participants, meanwhile, called for stricter punishment for crimes of inciting sectarian division.

Following the attacks, Saudi King Salman bin Abdulaziz pledged appropriate punishment for "any participant, planner, supporter or sympathizer" with the Shia mosque attack.

ISIL is a violent radical Sunni group that aims to establish an Islamic caliphate in territories under its control. Its cells are known to operate in Libya and Yemen, among a number of other Middle Eastern and North African states.