A Saudi interior ministry official says a suicide bomber detonated his belt during Friday prayers inside a Shi’ite mosque in the east of the kingdom.
Twenty worshipers were killed in the attack and 50 others wounded, according to hospital officials and witnesses.
A ministry statement said the bomber’s suicide belt had been hidden under his clothes.
No group had admitted they were to blame for the bombing which happened in the town of Al-Qudayh in the east of Saudi Arabia where most of the country’s minority Shi’ites live.
Tensions have risen in the region since a Saudi-led coalition started airstrikes in Yemen to prevent a advance by Houthi rebels who are mostly Shi’ite and allied to Iran.
Much of Yemen has been pushed to the brink of collapse since the Saudi-led operation began.Severe shortages of food, fuel and water are causing millions to suffer.
Friday’s blast was the first to target Shi’ite Muslims in Saudi Arabia since November when gunmen killed at least eight people on a religious anniversary celebration.