PHOTO: TIMES OF OMAN

RIYADH: Twenty people were killed as a suicide bomber blew himself up at a Shia mosque in eastern Saudi Arabia during Friday prayers, a hospital official said.



The official reached by telephone said more than 50 other people were wounded, including some who are in serious condition.



No one immediately claimed responsibility for the bombing, the first to target Shia Muslims in Saudi Arabia since November when gunmen killed at least eight people in an attack on a Shia religious anniversary celebration, also in the east.



The attack could further harm relations between Sunnis and Shias in the Gulf region, where tensions have risen during weeks of military operations in Yemen by a Saudi-led coalition against Shia Houthi fighters seen as proxies of regional Shia power Iran.



One witness described a huge explosion at the Imam Ali mosque in the village of al-Qadeeh.



He estimated there were at least 30 casualties in the attack, where more than 150 people were praying.



"We were doing the first part of the prayers when we heard the blast," worshipper Kamal Jaafar Hassan told Reuters by telephone from the scene.



Al-Arabiya television quoted a journalist at the scene as saying that at least six people were killed.



State news agency SPA quoted a security spokesperson confirming an explosion at a mosque in eastern Saudi Arabia, where most of the country's minority Shias live.



A spokesperson for the Saudi interior ministry could not immediately be reached for comment. A photograph posted on social media showed the mutilated body of a young man, said to be the suicide bomber.



Other pictures showed ambulances and bloodied victims being taken away on stretchers.



In April, Saudi Arabia said it was on high alert for a possible attacks on oil installations or shopping malls.



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



IS claims responsibility



The Islamic State group said in an online statement Friday that it carried out ‘a deadly suicide bomb attack at the mosque in Saudi Arabia's predominantly Shia Eastern Province’.



The statement said "the soldiers of the Caliphate" were behind the attack by a suicide bomber "who detonated an explosives belt" in the mosque in the Shia-majority city of Qatif.



It identified the bomber as Abu Amer al-Najdi, and published a picture of him.