Activists say Syrian forces have used nail bombs on protesters who took to the streets Friday, a day after Arab League peace monitors visited several flashpoint cities.

The Syrian Observatory for Human Rights says the ammunition was used to disperse thousands of demonstrators in the Damascus suburb of Douma. It says some protesters retaliated by throwing stones.

Activists also say forces killed five protesters in Daraa, while four people were killed in a government ambush near the Lebanese border.

On Thursday, the government said Arab League monitors “met a number of citizens” in the Damascus, Homs, Daraa and Hama regions.

But, activists said Syrian forces killed at least 25 people Thursday as the monitors fanned out across the country to check the government's compliance with pledges to end the crackdown and release political detainees.

On Friday, Syria's ally Russia said it is “satisfied” with the initial results of the Arab League observer mission. The foreign ministry said in a statement that the situation in the restive city of Homs “seems to be reassuring,” based on initial observer reports.

Syria pulled some of its tanks from Homs and released about 800 prisoners. But opposition leader Burhan Ghalioun said the government continues to hold more than 100,000 people, “some of them in military barracks and aboard ships off the Syrian coast.”

Syrian authorities agreed to the observers under international pressure and threats of Arab sanctions. The plan requires the government to give the monitors freedom of movement except for sensitive military sites.

The United Nations estimates 5,000 people have been killed since March in violence linked to Syria's unrest. Syria says armed terrorists are driving the revolt. It accuses them of killing 2,000 security personnel since March.