One the vice-presidents of the Indian Ocean nation of Comoros has survived an assassination attempt days before a referendum on constitutional reform.

Assailants opened fire on the car of Moustoidrane Abdou as he was returning to his home on the island of Anjouan.

Nobody was injured in the attack on Sunday morning, but the car was badly damaged.

The attack came a week before a controversial referendum that could allow President Azali Assoumani to extend his term in office, and abolish the vice-presidential posts.

Critics of the president have been detained and placed under house arrest during the referendum campaign, which has also seen violent clashes between protesters and security forces.

After more than 20 coups or attempted coups, the archipelago of islands that make up Comoros are trying to consolidate political stability and use tourism to climb out of poverty.