Algerian police in riot gear on Saturday surrounded about 500 protesters trying to stage a march through the capital inspired by uprisings in other parts of the Arab world in defiance of a ban.
A Reuters reporter at the scene said a group chanting "Algeria -- free and democratic!" tried to reach May 1 Square in the city centre to begin the protest march but were driven two blocks away by police using batons.
They were then corralled into the courtyard of a residential block, where police in helmets and protective gear surrounded them -- together with several hundred onlookers and some pro-government demonstrators.
The protest was organised by human rights groups, some trade unionists and a small opposition party. Algeria's main opposition forces were not taking part.
Large numbers of police had been mobilised to try to prevent Saturday's protest from going ahead. Dozens of police vans and military-style police armoured vehicles were dotted around the capital hours before the demonstration was supposed to begin.
On the streets approaching May 1 Square, near the city's port, police were lined up along the road while riot-control vehicles with water cannon on standby.
A police helicopter hovered over the centre of Algiers, a city of densely-packed whitewashed buildings sloping down towards the Mediterranean Sea.
"If the authorities are democratic, why are they not allowing us to march?" said a 52-year-old woman at the protest.
Police at the protest detained Belaid Abrika, a prominent opposition figure and campaigner for the rights of Algeria's large Berber minority.
The authorities had refused permission for the march, citing public order concerns, but said the opposition could instead rally in an officially sanctioned venue.
About 150 protesters held a protest last Saturday in May 1 Square and say they want to make it a weekly event until their demands for more democratic freedoms are met.
Many Algerians are unhappy with the government over high prices, unemployment and poor housing conditions.
Though the protests themselves have been too small to rattle the authorities, there have been signs of pressure building from inside the ruling establishment for substantial change, including a new government line-up.
ReutersGüncelleme Tarihi: 19 Şubat 2011, 15:16