Bahrain’s government called in forces from its Sunni neighbours to put down unrest by its Shia Muslim majority after protesters overwhelmed the police and blocked roads in a resurgence of mass protests seen last month.

Mr Nabeel al-Hamer, a former Information Minister and adviser to the royal court, said on his Twitter feed these troops were already on the island, a key United States ally and headquarters of the US Navy’s Fifth Fleet. Saudi officials declined comment.

Bahraini opposition groups including the largest Shia Muslim party Wefaq said any intervention by Gulf Arab forces on the island was a declaration of war and an occupation.

Analysts and diplomats say the largest contingent in any Gulf Cooperation Council (GCC) force would likely come from Saudi Arabia, already worried an uprising by Bahrain’s Shias would embolden restive Shias in its own Eastern Province, the centre of the oil industry.

“Forces from the Gulf Cooperation Council have arrived in Bahrain to maintain order and security,” Mr al-Hamer said.

Gulf Daily News, a newspaper close to Bahrain’s powerful Prime Minister, reported on Monday that forces from the GCC – a six-member regional bloc comprising Saudi Arabia, the United Arab Emirates, Kuwait, Qatar and Oman in addition to Bahrain – would protect strategic facilities.

The GCC forces would help maintain law and order, it said in a front page report.

“Their mission will be limited to protecting vital facilities, such as oil, electricity and water installations, and financial and banking facilities.”

Saudi-owned news network Al Arabiya also quoted an official source saying Bahrain would be supported by forces from the GCC, a military, economic and political alliance.

The reports come after Bahraini police clashes on Sunday with mostly Shia demonstrators in one of the most violent confrontations since troops killed seven protesters last month.

Bahrain has been gripped by its worst unrest since the 1990s after protesters took to the streets last month, inspired by uprisings that toppled the leaders of Egypt and Tunisia.

Any intervention by Gulf Arab troops in Bahrain is highly sensitive on the island, where the Shia Muslim majority complains of discrimination by the Sunni Muslim royal family.

Most Gulf Arab ruling families are Sunni and intervention could be seen by local Shias as an assault.

This, in turn, could encourage intervention by non-Arab Iran, the main Shia power in the region. Accusations already abound of Iranian backing for Shia activists in Bahrain, accusations they deny.

“Shias in states with large Shia populations, in particular Kuwait and Saudi Arabia, may intensify their own local anti-regime demonstrations,” said Mr Ghanem Nuseibeh, Partner at consulting firm Cornerstone Global.

“The Bahraini unrest could potentially turn into regional sectarian violence, that goes beyond the borders of the particular states concerned.” Reuters