Saudi Arabia executed 37 Saudis for terrorism-related crimes including attacks on security installations, the Interior Ministry said Tuesday.

The report said the executions were carried out by beheading and that two of the executed men’s bodies were publicly pinned to a poll for several hours in a process that is not frequently used by the kingdom and has sparked controversy for its grisly display. The government defends such executions as a powerful tool for deterrence.

The Interior Ministry statement said those executed had adopted extremist ideologies and formed terrorist cells with the aim of spreading chaos and provoking sectarian strife. It said the individuals had been found guilty according to the law and ordered executed by the Specialized Criminal Court in Riyadh, which specializes in terrorism trials, and the country’s high court.

The individuals were found guilty of attacking security installations with explosives, killing a number of security officers and cooperating with enemy organizations against the interests of the country, the Interior Ministry said.

The statement was carried across state-run media, including the Saudi news channel al-Ekhbariya. The statement read on the state-run news channel opened with a verse from the Quran that condemns attacks that aim to create strife and disharmony and warns of great punishment for those who carry out such attacks.

Those executed hailed from Riyadh, Mecca, Medina and Asir, as well as Shiite Muslim populated areas of the Eastern Province and Qassim. The executions also took place in those various regions.

The statement named all those executed, which included several from large families and tribes in Saudi Arabia.

The mass execution that took place Tuesday was ratified by a royal decree. It comes a day after the Islamic State group said it was behind an attack on Sunday on a Saudi security building in the town of Zulfi in which all four gunmen were killed and three security officers were wounded.

(AP)