CAIRO - Islamic State claimed responsibility for an attack at a Shi'ite Muslim mosque in Oman, where at least six people, including a policeman, were killed and 28 wounded, in a rare operation in one of the most stable countries in the Middle East, the group said in a statement on Telegram on Tuesday.

Any infiltration into Sunni-dominated Oman, which sits on one side of the Strait of Hormuz, a vital oil and gas shipping route, would raise fears of Islamic State trying to gain a foothold in the oil-rich Gulf.