Drawing inspiration from the revolt in Tunisia, thousands of Yemenis fed up with their president's 32-year rule demanded his ouster Saturday in a noisy demonstration that appeared to be the first large-scale public challenge to the strongman.
Clashes also broke out Saturday in Algeria, as opposition activists there tried to copy the tactics of their Tunisian neighbors, who forced their longtime leader to flee the country more than a week ago.
The protests in Yemen appeared to be the first of their kind. The nation's 23 million citizens have many grievances: They are the poorest people in the Arab world, the government is widely seen as corrupt and is reviled for its alliance with the United States in fighting al-Qaida, there are few political freedoms and the country is rapidly running out of water.
Still, calling for President Ali Abdullah Saleh to step down had been a red line that few dissenters dared to test.
In a reflection of the tight grip Saleh's government and its forces have in the capital, Saturday's demonstration did not take place in the streets but was confined to the grounds of the University of Sana.
About 2,500 students, activists and opposition groups chanted slogans against the president, comparing him to Tunisia's ousted President Zine El Abidine Ben Ali, whose people were similarly enraged by economic woes and government corruption. "Get out get out, Ali. Join your friend Ben Ali," the crowd chanted.
Police fired tear gas at the demonstrators, whose grievances include proposed constitutional changes that would allow the president to rule for a lifetime. Around 30 protesters were detained, a security official said.
Since the Tunisian turmoil, Saleh has ordered income taxes slashed in half and has instructed his government to control prices. He also ordered a heavy deployment of anti-riot police and soldiers to several key areas in the capital and its surroundings to prevent any riots.
Protests were also held in the southern port city of Aden, where calls for Saleh to step down were heard along with the more familiar slogans for southern secession. Police fired on demonstrators, injuring four, and detained 22 others in heavy clashes.
In Algeria, meanwhile, helmeted riot police armed with batons and shields clashed with rock- and chair-throwing protesters who tried to march in the capital, Algiers, in defiance of a ban on public gatherings.
At least 19 people were injured, the government said, but an opposition party official put the figure at more than 40.
Protest organizers at the headquarters of the opposition Rally for Culture and Democracy party draped a Tunisian flag next to the Algerian flag on a balcony where the march was to begin.
Riot police, backed by a helicopter and crowd-control trucks, ringed the exit to ensure marchers couldn't leave the building and struck those who tried to come out to take part.
Meanwhile, in Tunisia, the country's once-feared police staged a rally Saturday in the capital, demanding better salaries and insisting they're not to blame for shooting deaths among protesters who forced the North African country's longtime autocrat to flee. At least 2,000 police rallied in downtown Tunis.