Islamic State claimed responsibility for an attack at a Shi'ite Muslim mosque in Oman, the group said on Tuesday, which left at least nine people dead, including three attackers, a rare security breach in the oil-producing Gulf state.

The attack on Monday, which is unusual in the wealthy, Sunni Muslim-dominated Gulf states, raises fears that the Islamic State group may be trying to gain a foothold in new territory.

"Three suicide attackers from the Islamic State attacked last night a gathering of Shi'ite (Muslims) while they were practicing their annual rituals at a temple in the Wadi al-Kabir district in the (Omani) capital," according to group's statement, which cited three security sources.

The Islamic State fighters fired on Shi'ite worshippers and exchanged gunfire with Omani security forces until morning, the statement added.

Islamic State late on Tuesday published what it said was a video of the attack on its Telegram site.

The group also said that the attack left more than 30 Shi'ite Muslims and five Omani forces, including a police officer, killed or wounded.