There are people instigating divisions and separatism, we know them and they will be unmasked

President Bouteflika

President Bouteflika, in a televised speech, paid tribute to the victims - unofficially estimated at more than 50.

He accused unnamed groups both inside and outside the country of inciting extremism.

The clashes, which pitted security forces against local youths, were sparked by the killing of a teenage student in police custody.

Opposition threat

Mr Bouteflika said the inquiry, led by members of civil society, would be "totally free and transparent".

President Bouteflika: Facing Islamist and now Berber challenges

"These events did not happen by chance, there are people instigating divisions and separatism, we know them and they will be unmasked in time," he said without elaboration.

Mr Bouteflika has been criticised by the mainly Berber political party, the Rally for Culture and Democracy (RCD), for not being in control of the security forces, which it accuses of using excessive force.

The party has threatened to pull out of the government coalition over the way the clashes have been handled. A final decision will be announced on Tuesday.

Pitched battles

On Saturday and Sunday, there were pitched battles between masked stone-throwing demonstrators and police firing teargas in the city of Tizi Ouzou.

It is the main city of the fiercely independent Berber region, about 90km (55 miles) east of Algiers.

The Berbers, who make up about a third of the population, have long opposed Algeria's military-backed government and want their language to have an equal status to Arabic.

Correspondents say their main concerns are currently social ones, arising from mass unemployment and housing shortages, but the violence was sparked by a young Berber man in police custody.

The riots, which spread like wildfire to villages across the region, coincided with the anniversary of a state crackdown of the Berber Spring in 1980.

On Saturday, doctors at Tizi Ouzou's main hospital said four demonstrators had been killed by gunfire. One of the dead had been shot at point blank range in the head, a nurse said.

On Saturday alone, at least 29 people were killed in the Kabylie region, local residents said.

In Bejaia, further to the east, a protest march on the police station degenerated into violence, residents said.