Riot police officers stifled a protest in Algeria's capital on Saturday by hundreds of people voicing the same demands for change that have helped topple two of the region's autocratic governments over the last month.

Gathering in the central May 1 Square, demonstrators in Algiers chanted “Bouteflika out!” referring to President Abdelaziz Bouteflika, who has ruled Algeria with a tough hand since 1999, maintaining power through elections that opposition figures say were rigged. The rally's organisers said thousands had taken part but news agencies and the government gave vastly differing figures.

Witnesses said thousands of riot police officers with clubs had blocked the demonstrators from carrying out a planned march in the centre of the whitewashed seaside capital, which was otherwise tense and deserted on Saturday. By late afternoon, with the last of the demonstrators gone, the square was still sealed off by police officers, and dozens of armoured police vehicles remained in the neighbourhood.

It was unclear on Saturday what, if any, long-term implications the protest would have for Mr. Bouteflika's government; outbursts of civil unrest have been frequent here for decades. But the large-scale deployment of the police and recent concessions — Mr. Bouteflika has promised to lift a longstanding state of emergency — show the government is wary of the contagion of unrest in neighbouring countries. Many demonstrators were arrested, although there were also conflicting numbers for those detained.

The government news agency minimised the “unauthorised” demonstration's significance, quoting the police as saying that only 250 had taken part. But one of the organisers, Said Sadi of the opposition Rally for Culture and Democracy, said that Saturday's event was a “great success” and that it would not be the last such demonstration. “When you mobilise 30,000 police in the capital, that's a sign of weakness, not strength,” he said. The figure could not be independently verified. But witnesses suggested the police far outnumbered the protesters.

With the police still out in force, knots of men watched them silently from doorways in the chill dusk. Among them were suggestions that persistent grievances of large-scale unemployment, reports of government corruption, heavy-handed police tactics had not been mitigated by the demonstration's suppression.

On Friday, several people were wounded outside the office of the main opposition group by security forces as they were celebrating the resignation of President Hosni Mubarak of Egypt.

In Algeria, several antigovernment protests broke out in early January, including some in which demonstrators clashed with members of the security forces. The protests began after prices rose sharply. In 2009, there were riots in Algiers over high unemployment and housing shortages. Algeria's government has operated under a state of emergency for nearly two decades. Its battle with Islamic militants reached a peak in a civil war in the 1990s, in which as many as 200,000 people were killed. That conflict began after the military-backed government cancelled elections that an Islamist party appeared poised to win.

In Yemen on Saturday, a small antigovernment protest in the capital, Sana, quickly drew several thousand supporters before they were attacked by pro-government forces, witnesses said. The protests began when a group of Sana University students gathered in front of the campus, writing banners in support of the Egyptian uprising, said Faysal al-Namsha, an opposition supporter who was there. When the crowd grew to 3,000 people, Namsha said, men in plain clothes believed to be security forces attacked the demonstrators with clubs and sabers. The students later marched toward Tahrir Square, where supporters of President Ali Abdullah Saleh, some carrying his picture, attacked them again.

Several Arab leaders also made their first public comments on the revolt in Egypt, a day after mass demonstrations forced Mr. Mubarak to resign. Saudi Arabia, which has been outspoken in its defence of Mr. Mubarak, said it welcomed a “peaceful transition of power” in Egypt, and expressed “hope in the efforts of the Egyptian armed forces to restore peace, stability and tranquillity.” In Bahrain, Al-Watan quoted the government as saying that the kingdom was interested in developing its relationship with Egypt and was confident in the ability of the Egyptians to establish stability. King Hamad Bin Isa al-Khalifa of Bahrain, who is facing street protests planned for Monday, decided to give the equivalent of $2,560 to each Bahraini family. He is expected to announce reforms soon.

In Tunis, the cradle of the revolution, hundreds turned out on Friday and again on Saturday to celebrate Mr. Mubarak's ouster. Many said they hoped Algeria would be the next to fall. On Friday evening, young people in Tunis sang an Algerian soccer chant: “One-two-three, Algerie!”

(Nada Bakri contributed reporting from Beirut, and Thomas Fuller from Tunis.) — New York Times News Service

More In: Comment | Opinion