A car that struck and injured at least one Bahraini anti-government protester is surrounded by others on Monday at the Bahrain Financial Harbor in Manama. -AP Photo

MANAMA: Three hardline Bahraini Shia Muslim groups said on Tuesday they had joined together with the goal of bringing down the Bahraini Gulf Arab monarchy and setting up a republic.

The move by the three Shia groups is likely to be seen by the ruling Sunni al-Khalifa family as an escalation and raises the chances of a renewed security crackdown against mainly Shia protesters.

The new movement, made up of groups much smaller than the main opposition group Wefaq, widens a split within the broader Shia opposition movement that is demanding more representation and better access to jobs within the system.

“This tripartite coalition adopts the choice of bringing down the existing regime in Bahrain and the establishment of a democratic republican system,” the three groups said in a joint statement.

Bahrain has been gripped by the worst unrest since the 1990s after a youth movement emboldened by protests across the Arab world took to the streets last month. Seven were killed in clashes with security forces, but the situation has since been calmer.

The new Shia opposition bloc includes Al Haq, Wafa and the Freedom Movement and calls itself the “Coalition for a Republic”.

The groups held a news conference at the protesters' camp, calling for peaceful change through civil disobedience and civil resistance.

The majority of Bahrainis are Shias but the island, home to the US Navy's Fifth Fleet and located just off the coast of the world's largest oil exporter, is led by the US-backed al-Khalifa Sunni Muslim royal family.

Thousands are still camped out in a square in Manama, with many of them demanding the ouster of Bahrain's ruling family.

Haq and its leader Hassan Mushaimaa have questioned the legitimacy of the ruling family in the past and the government has arrested its leaders several times in recent years, including during a security crackdown last August.

But Mushaimaa and other Haq leaders were pardoned by the King after the protests erupted in Bahrain and Mushaimaa returned to Bahrain from London last month.

Bahrain's largest Shia group Wefaq, which draws larger support numbers than Haq and the youth movement, is more moderate and has only called for the resignation of the government and a true constitutional monarchy that cedes more power to the people.