Syrian forces on Friday fired on protesters holding the largest opposition marches yet in Aleppo, a sign of rising anti-regime sentiment in the country's biggest city, which has largely remained supportive of President Bashar Assad throughout the 15-month uprising.
The head of the U.N. observer mission in Syria warned that neither his team nor armed action could solve the country's crisis, and called on all sides to discuss a solution. But the regime kept up its assaults on opposition areas and protests, while the head of Syria's largest exile opposition group dismissed the U.N.'s plan as unrealistic.
Anti-regime protests in Aleppo have been growing since a raid on dormitories at Aleppo University killed four students and forced the temporary closure of the state-run school earlier this month.
The May 3 raid was an unusually violent incident for the northern city, a major economic hub, where business ties and large minority populations have kept most residents on the side of the regime _ or at least unwilling to join the opposition.
On Thursday, some 15,000 students demonstrated outside the gates of Aleppo University in the presence of U.N. observers, before security forces broke up the protest.
Even bigger numbers took to the streets Friday. Aleppo activist Mohammad Saeed said it was city's largest demonstration yet, with more than 10,000 people marching in the Salaheddine and al-Shaar districts and nearly as many more elsewhere in the city.
"The number of protesters is increasing every day," Saeed said. He added that several people were wounded when government forces fired tear gas and live ammunition to disperse the rallies.
"It's a real uprising happening in Aleppo these days," said Rami Abdul-Rahman, head of the Britain-based Syrian Observatory for Human Rights.
Thousands of people elsewhere in the country also staged anti-government rallies in solidarity with Aleppo. Friday is the main day of protests across Syria and this week's demonstrations were dedicated to "The Heroes of Aleppo University."
Opposition activists said security forces opened fire on protests in several locations, including the Damascus suburbs and the central city of Hama. They also said the regime shelled the central town of Rastan, which rebels have controlled since January.
Amateur videos posted online Friday showed shells whizzing through the air and slamming into residential areas in Rastan, sending up clouds of smoke.
The Observatory also reported three people shot dead by security forces in the al-Tadamon neighborhood in southeast Damascus.
More than 200 U.N. observers are in Syria as part of a peace plan to end the crisis. The head of the observer mission cautioned Friday that neither his mission nor armed force can stop the bloodshed without genuine talks between the two sides.
No number of observers can achieve "a permanent end to the violence if the commitment to give dialogue a chance is not genuine from all internal and external actors," Maj. Gen. Robert Mood told reporters in Damascus.
International powers have pinned their hopes on the peace plan for Syria that special envoy Kofi Annan brokered in April. The plan paved the way for the U.N. observers, and it calls for a cease-fire and dialogue to end the conflict.
The U.N. estimated in March that the violence in Syria has killed more than 9,000 people. Hundreds more have been killed since then as a revolt that began in March 2011 with mostly peaceful calls for reform has transformed into an armed insurgency.
Both sides have flouted the cease-fire, raising concerns that the peace plan is ineffective and the violence is spinning out of control.
Annan's spokesman, Ahmad Fawzi, said in Geneva that the envoy would be visiting Syria soon, but did not give a date. A high-ranking military adviser to U.N. Secretary-General Ban Ki-moon, Babacar Gaye, arrived in Damascus on Friday.
But dialogue seems a distant hope. The opposition says it will accept nothing less than the regime's ouster, and the government brands its opponents as terrorists.
On Friday, the head of Syria's largest exile opposition group, the Syrian National Council, said he had little hope for Annan's plan.
"We have no illusions on this mission," Burhan Ghalioun told The Associated Press in Paris, where he is based. "In reality, it's a mission which was done in order to hide the lack of international consensus. That's all."
Assad says the popular will is not behind the country's uprising, and claims that foreign extremists are driving the unrest to destroy the country. He has pointed to a rise in rebel attacks on military targets as well as suicide bombings in major cities to bolster his case.
The most recent bombing, which targeted an intelligence building in Damascus on May 10, killed some 55 people and has raised fears that extremist groups are exploiting the chaos in Syria for their own purposes.
At the United Nations, Ban said he had such fears.
"The recent terrorist attacks in Damascus suggest that these attacks were carefully orchestrated," he said. "Having seen the scale and sophistication of these terrorist attacks, one might think that this terrorist attack was done by a certain group with organization and clear intent. I have strongly condemned these terrorist attacks."
In Damascus, Mood spoke out against the rising violence.
"I am more convinced than ever that no amount of violence can resolve this crisis," he said. "I am concerned about the incidents where explosives, improvised devices are targeting innocent civilians, innocent people because it is not going to help the situation."
Karam reported from Beirut. AP writers John Heilprin in Geneva, Albert Aji in Damascus, Syria, Ron DePasquale in New York and Catherine Gaschka in Paris contributed reporting.