DUBAI (Reuters) - Bahraini authorities have arrested four members of cell behind a bomb attack on an oil pipeline, the interior ministry said on Wednesday, adding two of the group had been trained in Iran, an adversary of the Gulf Arab state.

Iran denies any role in Bahrain’s unrest.

The explosion on November 10 caused a fire at Bahrain’s main pipeline near Buri village, 15 km (10 miles) from the capital Manama, forcing the evacuation of residents.

A ministry statement said authorities had arrested four people, two of whom had received intensive training in Iran to carry out attacks to harm Bahrain’s economy and its oil pipeline.

“Immediately after their return from Iran, they planned and got ready to blast the oil pipeline ...in addition to committing a series of other terrorist acts. They checked out the location and remotely bombed the pipeline,” the ministry said.

Authorities were searching for three others “involved in the financing, planning, and implementation” behind the attack, the statement said, two of which live in Iran.

A key Western ally and host to the U.S. Fifth Fleet, Sunni Muslim-ruled Bahrain has for years grappled with protests mainly by members of its Shi’ite Muslim majority who demand a bigger share in running the kingdom.

Several Bahraini dissidents reside in Iran, calling for armed struggle to uproot Bahrain’s ruling Al Khalifa monarchy in a holy war.

Iran has called accusations that it had any role in supporting violent acts in Bahrain “baseless and fabricated”, but it has allowed the exiled Bahrainis to promote their ideas on Iranian official media and hold mourning ceremonies for those involved in deadly attacks in the country.