Jeddah: 18 people were injured and four killed on Friday when a suicide bomber attacked a mosque in Shiite-populated eastern Saudi Arabia, state media said.

Quoting an interior ministry spokesman, the Al-Ekhbariya news channel gave the new toll, up from two dead and seven injured earlier. Residents said the mosque belonged to the minority Shiite community.

In a written statement, the ministry said security personnel stopped two bombers from getting inside the Al-Rida mosque in the Mahasen neighbourhood of Al-Ahsa city during the main weekly prayers.

It said, "When security approached to intercept them, one of them responded by blowing himself up at the mosque entrance while an exchange of fire took place with another. He was injured and arrested. A suicide belt was found in his possession."

Since deadly attacks claimed by the Islamic State group last year against Shiite mosques in the kingdom's east, security has been beefed up, including the presence of community guards who check visitors to houses of worship.