The Arabian Peninsula nation's opposition, inspired by the revolt in Tunisia and the ongoing uprising against President Hosni Mubarak in Egypt, had called for a "day of rage" against the rule of President Ali Abdullah Saleh, who has held his title since 1978 and has been accused of corruption and mismanagement. Saleh and his supporters sought to upstage the protesters by holding a simultaneous counter-demonstration across town.
The two rallies drew tens of thousands of people and, unlike in Egypt or Tunisia, unfolded largely peacefully with no major arrests or clashes, according to a Yemeni official. The day's relative calm suggested that the political passions unleashed by the uprisings in Egypt and Tunisia will play out in different countries in different ways.
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In the North African nation of Algeria, longtime President Abdelaziz Bouteflika announced Thursday that he would soon end a 19-year state of emergency that has restricted civil liberties as activists began calling for Feb. 12 protests against his rule, according to the country's official news agency.
Saleh has scrambled to make concessions to the Yemeni opposition. On Wednesday, he vowed to not run again when his term ends in 2013 or position his son as his successor. He also promised to begin broad talks with the opposition about possible reforms.
Ahead of the anti-government protest Thursday and another on Sunday, he imposed none of the repressive moves used by Mubarak or Tunisia's former President Zine el Abidine ben Ali, such as shutting down the Internet.
"President Saleh offered bold concessions that are in the interest of the country," said Mohammad Basha, a spokesman for the Yemeni Embassy in Washington, in response to an e-mail inquiry. He is "promoting a peaceful political struggle and avoiding a chaotic political showdown with the opposition. People have the democratic right to assemble and voice their concerns."
The Obama administration and the European Union have praised Saleh's pledges to reform. But his opponents have reacted skeptically.
"We see the president's speech yesterday as positive, but this demonstration is calling for a truly honest government, not just concessions," said Muhammad Abdul Malik Mutawakkil, a leader of the opposition Islah, or Reform, Party. "They must continue until we reach that goal."
The protests also add to the troubles of a nation already facing multiple security challenges. The government is battling an insurgency by Houthi rebels in the north, a separatist movement in the south and an Al Qaeda threat.
"Our ceremony is quite peaceful and we will not let any provocateurs hijack our gathering," said Ibrahim Mohammed Ali Azan, an anti-government protester. "But if the government persists on its course, how can they expect these demonstrations to remain peaceful?"
The pro-government rally, which appeared to have been set up hastily the night before, received official logistical support. Soldiers guarding the demonstration route from the capital Sana's old city to Tahrir Square mingled amicably with the thousands holding portraits of Saleh. Huge tents and loudspeakers lined the way. "With our souls, with our blood we will sacrifice for you, oh Ali," they chanted, in support of Saleh.
"Ali Abdullah Saleh is the lion of all the Arabs, not a coward like Mubarak or Ben Ali," said Abdul Rahman Ghanam, 68. "He is our hero, and we will do anything to protect him."
The opposition, led by a coalition of well-organized and vocal political parties and groups, had hoped to stage a march along the same route as the pro-government rally. Instead, it held its gathering in the university district in a western part of the capital. A large cordon of anti-government activists formed a human chain to guard against any pro-government infiltrators.
Protesters held banners urging Saleh to "Go! Go! Go!" and portraits of Mohammed Bouazizi, the 26-year-old Tunisian college graduate who made a living selling produce and who set himself on fire Dec. 17 after being harassed by authorities.
That act of protest and desperation sparked the Tunisian uprising that toppled Ben Ali and captivated the Arab world, especially the poor, frustrated young working class men largely discarded by political elites.
"We are demanding life itself, because under the conditions of the country now, we're just not living," Yusuf Amri, a labor activist, said at Thursday's rally.
Protesters described Saleh's promises of reform as "business as usual" and blamed him for most of the country's troubles.
"All that happens in the south, all that happens with the Houthis in the north, the president is behind it," said Ali Hamdi, 22, a student who was among the anti-government protesters. "In order for these conflicts to stop, the president must go."
As the protest wound down, loudspeakers urged attendees to leave peacefully and pleaded with them not to clash with ruling party supporters loitering around the area.
Times staff writer Daragahi reported from Beirut and special correspondent Browning from Sana, Yemen.