Tens of thousands of protesters poured into streets across Syria on Friday, braving a government onslaught of tear gas, nail bombs and gunfire that activists said killed at least 16 people. The demonstrations marked a display of renewed vigor for opponents of President Bashar al-Assad, who are eager to make their case during a visit by Arab League observers.

Crowds of demonstrators, dancing and singing, gathered in parts of the Damascus suburbs and the cities of Homs and Hama, where the monitors were visiting, in an apparent bid to draw international attention to the brutality of Assad’s crackdown on dissent.

In Douma, outside Damascus, more than a dozen soldiers were said to have defected during protests there, shooting at their commanders before escaping, while thousands of people clustered in the suburb’s main square, singing, “We don’t want you, Assad,” and waving banners asking the Arab League to help them. Soldiers later fired tear gas and nail bombs into the crowd, causing more than 70 injuries, said one member of the Local Coordination Committees activist network.

The monitors’ presence has reinvigorated a protest movement that had been flagging, according to activists.

“When they saw the Arab League, they felt confident,” said Rami Abdulrahman of the London-based Syrian Observatory for Human Rights. He added, however, that the approximately 60 observers in the country have not been able to achieve their stated mission of overseeing an agreement for troops to withdraw from the cities, end the use of force against peaceful protesters and free political prisoners.

Many Syrians have expressed disappointment with the role played by the monitors, but they have continued to try to protest in areas where the monitors can see them.

The activist in Douma said observers stood on the steps of a mosque during the demonstration there and spoke with people in the crowd about protester deaths, abuse in detention, the searching of houses and electricity cuts. But he, too, voiced skepticism about their role.

“The mission was for one thing: to make the regime stop killing us,” he said. “Until now, the regime did not do that, so I am not generally hopeful for the mission.”

Wissam Tarif, a human rights activist with the Avaaz organization, said that protests had grown since the observers arrived, not because Syrians felt any safer in the streets but because they wanted to be visible.

“The people are willing to take the risks to show the Arab League what is happening,” he said.

Tarif added that activists had told Avaaz researchers that three people in Homs were arrested after speaking with the observers earlier this week, including one woman whose son was in detention.

A nine-month crackdown by Syrian forces on the scattered protest movement has killed more than 5,000 people, according to a United Nations estimate, and the opposition has become increasingly militarized.

The death toll has continued to rise since the Arab League delegation arrived more than a week ago, with more than 150 people killed, including at least 34 who died or were found dead Friday, according to Abdulrahman, the London-based campaigner. Friday’s countrywide toll included at least 27 civilians, two defected soldiers and five members of the security forces, he said.

Heavy tanks and artillery have partially withdrawn from cities, although some protesters assert that they have been hidden in places across the country, including in the mountains in northwestern Idlib province, rather than returned to military bases.

An activist in Damascus said that since a double car-bombing that killed more than 40 people last week, the capital has filled with checkpoints and snipers have been stationed atop buildings.

The opposition military operations also appear to be continuing. A video uploaded Wednesday purported to show armed rebels attacking vehicles full of security forces in Daraa, the southern city where the uprising began. The five security personnel who died Friday were killed in an ambush outside Homs, Abdulrahman said.

Syrian authorities tightly control journalists’ access to the country, making it impossible to verify information.

The Free Syrian Army, a loose group of defectors and armed rebels commanded by exiled former Syrian officers, said Friday that it has suspended operations to allow the Arab League to operate.

“We want to give the Arab League mission a chance and remove any pretext for the regime to blame us for bloodshed similar to the Damascus bombings,” Col. Malik Kurdi said by telephone. He said he hoped the delegation would accurately record the situation in Syria and call for international intervention by the U.N. Security Council.