Algerian private television channel Al Atlas TV, which has strongly criticised the government, said on Wednesday that it had been ordered to stop broadcasting after police raided its headquarters.

Al Atlas information director Ghoul Hafnaoui told AFP that the satellite channel went off the air in mid morning, "under orders from the authorities," a day after police searched its premises and seized equipment.

The public prosecutor ordered the search as part of an investigation whose purpose has not been made known, Hafnaoui said.

"We were searched on Tuesday afternoon. The 45 journalists working for the channel were held for four hours inside the headquarters," in the Birkhadem district of the capital, he added.

Uniformed and plainclothes police took around 10 cameras from the building, while security forces also visited the channel's studios in Baba Ali, in south Algiers, which they sealed off.

Hafnaoui charged that the move was a response to programmes critical of the government, in the run-up to next month's presidential election.

"Our editorial line upsets the regime. Our channel frequently criticises its current policies," Hafnaoui said.

Ailing President Abdelaziz Bouteflika last week confirmed that he would seek a fourth term in office, a move which has sparked anger and derision in Algeria due to his fragile health.

His critics have charged that the 77-year-old leader, hospitalised for three months in Paris last year after suffering a mini stroke and very rarely seen in public, is in no fit state to run the country.

The government allowed several satellite TV channels to open studios in Algiers last year, and the national assembly passed a new broadcast law in January opening the sector up to the private sector after a 50-year state monopoly.

But the law has yet to come into force.

Reporters Without Border ranked Algeria 125th out of 179 countries classified in its 2013 world press freedom index.