Political violence killed at least 40 people across Syria on Friday, antigovernment activists said, as protesters took to the streets demanding a "no fly" zone to protect civilians seeking the ouster of President Bashar Assad.
It was the highest reported Friday death toll in months. Protests after Friday's midday Muslim prayers have become a weekly occurrence in Syria since mid-March, when the demonstration movement began.
Anti-Assad activists blamed the deaths on security forces attacking peaceful marchers. There was no word from Syrian authorities, but they have repeatedly blamed the violence on armed "terrorists," who they say are part of a conspiracy linked to the United States and its allies in the region.
Protest rallies erupted Friday across the country, activists said, including in the suburbs of the capital, Damascus, the west-central cities of Homs and Hama, and the northeastern city of Dair Alzour, near the Iraqi border.
Syria's opposition movement also includes an armed element, including former army soldiers who have switched their loyalty, activists say. Some fear that the Syrian conflict is becoming more militarized and could escalate into a full-fledged insurgency or civil war.
Political violence in Syria has left more than 3,000 dead, according to the United Nations. The government says more than 1,100 security forces have been killed.
The theme set by organizers of Friday's protests was a call for the imposition of a no-fly zone, like that used against former Libyan leader Moammar Kadafi. Kadafi's capture and death last week have provided inspiration the Syrian protest movement, activists say.
Foreign countries are unlikely to intervene in Syria as they did in Libya. Russia and China, both members of the Security Council, have vetoed a U.N. resolution that they feared could have led to military action against their ally.
Many Syrian opposition groups also are opposed to foreign intervention, fearing that it could polarize the nation and galvanize nationalist sentiments in favor of Assad.
Though the Obama administration has called for Assad to step down, the White House has said intervention is not in the cards.
"The vast majority of the Syrian opposition continues to speak in favor of peaceful, nonviolent protest and against foreign intervention of any kind, and particularly foreign military intervention into the situation in Syria, and we respect that," State Department spokeswoman Victoria Nuland told reporters this week.
However, Sen. John McCain (R-Ariz.) and others have raised the possibility of foreign intervention in Syria, especially now that the NATO mission in Libya is almost finished.
On Friday, amateur video uploaded to YouTube purportedly showed protesters marching down a street in Damascus' Midan neighborhood, clapping their hands and chanting, "The people want a ban on flying."
Another clip, said to have been filmed in the southern province of Dara, depicts a large crowd calling for a no-fly zone to a background drumbeat.
Friday's violence, activists said, was most severe in Homs, where 21 were reported killed, and Hama, where 14 were said to have died. Both cities have been the site of intense conflict in recent weeks.
The official Syrian government news agency, SANA, said an unspecified number of law enforcement officers were injured Friday by gunfire in Hama. No further details were given.
Syria has restricted media access, making it difficult to assess contradicting claims and casualty numbers.
In Syria's second-largest city, Aleppo, anti-government activists said security forces attacked a sit-in on Friday, firing tear gas.
But SANA denied that there was unrest in Aleppo, a major commercial hub. "The city is living a normal Friday," it said.
In Dair Alzour, thousands took to the streets after Friday prayers, according to Abdallah, an opposition activist in the area who declined to give his last name for safety reasons.
The activist coalition Local Coordinating Committees said that security forces were firing randomly at houses and people in the northwestern city of Jisr Shughur in Idlib province, while pro-government forces in the coastal city of Latakia were besieging a neighborhood, activists said.
Sandels is a special correspondent.