A family member of a victim mourns at the mosque in al-Qadeeh village. (Source: Reuters) A family member of a victim mourns at the mosque in al-Qadeeh village. (Source: Reuters)

A suicide bomber killed 21 worshippers during Friday prayers in a packed mosque in Shia-dominated area of eastern Saudi Arabia, residents and the health minister said, in an attack claimed by the Islamic State militant group.

It was one of the deadliest assaults in recent years in the kingdom, where sectarian tensions have been frayed by nearly two months of Saudi-led air strikes on Shia Houthi rebels in neighbouring Yemen.

More than 150 people were praying when the huge explosion ripped through the Imam Ali mosque in the village of al-Qadeeh, witnesses said.

A video posted online showed a hall filled with smoke and dust, with bloodied people moaning with pain as they lay on the floor littered with concrete and glass. More than 90 people were wounded, the Saudi health minister told state television.

“We were doing the first part of the prayers when we heard the blast,” worshipper Kamal Jaafar Hassan told Reuters by phone.

It was the first attack targeting minority Shias since November when gunmen opened fire during a religious celebration in al-Ahsa, also in the east where most of the group live in predominantly Sunni Muslim Saudi Arabia.

Islamic State said in a statement that one of its suicide bombers identified as Abu ‘Ammar al-Najdi carried out the attack using an explosives-laden belt that killed or wounded 250 people, US-based monitoring group SITE said on its Twitter account.

A photograph posted on social media showed the mutilated body of a young man, said to be the bomber.

The Saudi Interior Ministry described the attack as an act of terrorism and said it was carried out by “agents of sedition trying to target the kingdom’s national fabric”, according to a statement carried by state news agency SPA.

The agency quoted an Interior Ministry spokesman as saying that the bomber detonated a suicide belt hidden under his clothes inside the mosque.

“Security authorities will spare no effort in the pursuit of all those involved in this terrorist crime,” the official said.

A hospital official said that “around 20 people” were killed in the attack and more than 50 were under treatment at the hospital, some of them suffering from serious injuries.

In Yemen, a bomb at a Houthi mosque in the capital Sanaa on Friday was also claimed by Islamic State.

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