AKIPRESS.COM - The king of Saudi Arabia warned his country would strike with an "iron hand" against people who preyed on youth vulnerable to religious extremism, a day after suicide bombers struck three cities in an apparently coordinated campaign of attacks, Reuters reports.

In a speech marking Eid al-Fitr, the holiday that celebrates the end of the Islamic holy month of Ramadan, King Salman said a major challenge facing Saudi Arabia was preserving hope for youth who faced the risk of radicalization.

"We will strike with an iron hand those who target the minds and thoughts... of our dear youth," Salman, 80, said.

Four security officers were killed in Monday's attacks that targeted U.S. diplomats, Shi'ite Muslim worshippers and a security headquarters at a mosque in the holy city of Medina. The attacks all seem to have been timed to coincide with the approach of the Islamic Eid holiday.

The U.N. human rights chief on Tuesday described the bombing outside the Prophet Mohammed's Mosque in Medina as "an attack on Islam itself" and many Muslims expressed shock that their second-holiest site had been targeted.

No group has claimed responsibility but Islamic State militants have carried out similar bombings in the U.S.-allied, Sunni Muslim-ruled kingdom in the past year, targeting minority Shi'ites and Saudi security forces.

Zeid Ra'ad al-Hussein, the U.N. High Commissioner for Human Rights and a member of the Jordanian royal family, delivered his remarks via a spokesman in Geneva.

"This is one of the holiest sites in Islam, and for such an attack to take place there, during Ramadan, can be considered a direct attack on Muslims all across the world," he said. "It is an attack on the religion itself."