Nigerian police have arrested about 200 suspected members of the militant Yoruba group which is blamed for recent ethnic violence.

Mike Okiro, police commissioner for Lagos state, said some of the suspects - believed to be members of the Odua People's Congress (OPC) - would be charged with arson and murder.

"Those arrested are people involved in the murder of a senior police officer, for bathing two other officers with acid and for vandalising a police station," he said.

The OPC is demanding greater autonomy for the Yoruba people, who are Nigeria's second-largest ethnic group, and the dominant group in the south-west.

The past year has seen a succession of violent ethnic clashes in Lagos and other south-western cities, as well as in the northern city of Kano, where Yorubas form a substantial minority.

Most of the fighting has involved Yorubas and Hausas, the country's largest ethnic group who originate in the north, but who also wield considerable economic power in many south-western towns.

North-south rift

The OPC arrests come after President Olesegun Obasanjo accused the governor of Lagos state, Bola Tinubu, of not taking strong enough action against the Yoruba militants.

Following a heated public row with the Lagos governor, President Obasanjo threatened to impose a state of emergency if the fighting continued.

But the governors of Yoruba states have criticised the threat, saying the OPC was not responsible for the troubles, and that people were being paid to masquerade as OPC members.

Meanwhile, in northern Nigeria, a committee of elders has urged the president to take stronger measures to stop the violence.

The head of the committee, the former civilian president Alhaji Shehu Shagari, said if these fail a state of emergency should be declared.