DUBAI (Reuters) - Bahrain said on Wednesday a bomb attack on a police bus which killed an officer and wounded nine last month was carried out by a militant cell trained by its arch-foe Iran.

After authorities quashed Shi’ite Muslim-led “Arab Spring” protests on the Sunni-ruled island in 2011, militants have launched deadly bombing and shooting attacks against security forces that Bahrain blames on Tehran’s Shi’ite theocracy.

Iran denies any role in Bahrain’s unrest.

There was no immediate Iranian reaction to Wednesday’s Bahraini interior ministry statement, which added that authorities had arrested one member of the cell while others were fugitives in Iran.

“The terrorist cell received extensive training in Iranian Revolutionary Guard camps on the use and manufacture of explosives and firearms, as well as material and logistical support,” the ministry said.

Bahrain said earlier this week that an explosion at its main oil pipeline on Friday was caused by “terrorist” sabotage, linking the unprecedented attack to Iran.

A key Western ally and host to the U.S. Fifth Fleet, Gulf Arab monarchy Bahrain has for years grappled with protests and sporadic violence coming from its Shi’ite majority.