An Arab League committee traveled to Damascus on Thursday to discuss the logistics of a planned mission to monitor an increasingly violent uprising and the response of the Syrian security forces, which has been widely condemned as disproportionately brutal.

Following the imposition of sanctions by the Arab League, the government of President Bashar al-Assad agreed Monday to implement a plan for hundreds of observers to enter the country. They are set to report on a situation that activists say is a bloody crackdown on dissent and that Syrian authorities say is a battle against armed gangs, foreigners and extremists.

The committee begins its work after a surge of violence in the northwest, where opposition groups say hundreds of people have been killed, although they disagree on whether the casualties were peaceful civilians, armed dissidents or defected soldiers.

Wissam Tarif, a human rights activist with the Avaaz group and one of the nominated observers, said he fears that Syrian authorities will endeavor to control which monitors are allowed into the country and what they see there.

He said the committee would discuss whether monitors would be able to provide their own security, whether they would have the liberty to move without giving notice to Syrian officials, and from which groups and countries the approximately 500 observers would be drawn.

“I am concerned that they will negotiate name by name, and I know for sure that they are very tough on liberty of mobilization and on the the security issue,” Tarif said. “The Arab League should make it very clear that they can’t drag this into weeks and weeks of negotiations.  . . . The Syrian people do not have the luxury of time.”

News of the death toll near the northwestern city of Idlib, which lower estimates put at about 200, has prompted outrage from the international community.

“Only two days following the Assad regime’s decision to sign the Arab League initiative, they have already flagrantly violated their commitment to end violence,” said a statement by the White House on Wednesday, which also warned of additional steps to pressure the Assad regime to stop the violence.

The Turkish government, which has become one of Assad’s harshest critics, said the situation in the country was becoming a bloodbath, while the French Foreign Ministry spokesman called the fighting “a massacre of unprecedented scale.”

The Syrian National Council, the most prominent opposition group outside the country, has formerly focused on nonviolent solutions, but it sharpened its tone in the wake of the violence, calling for an emergency meeting of the Arab League and for international forces to guarantee safe zones in Syria and force Syrian soldiers to withdraw from affected areas.

The violence near Idlib continued Thursday, said Ali Hassan, a representative of the Syrian Revolution General Commission, which represents several protest groups inside Syria. The Idlib area, one of the poorest in the country with most people depending on agriculture, was hit hard when security forces burned farms and killed livestock this year, according to YouTube videos, and anti-government sentiment is high.

Hassan said 15 civilians and an imam were killed Thursday in the area, in an act of collective punishment for having given shelter to members of the group of defected soldiers and armed rebels known as the Free Syrian Army. The area is hilly and wooded, he said, making it an ideal tactical location.

Alaa Yousif, a spokesman for a revolutionary group in Idlib, said the situation was “miserable, miserable, miserable,” when contacted by telephone. “This is a siege, a curfew, gunfire, no water or bread.” He, too, said that the army had initially been attacking defected soldiers but that they were now all killed or had fled, and that it was civilians and demonstrators who were being shot at by hundreds of army tanks.

“They are not detaining or arresting anyone, they are killing them right away,” said Yousif, calling for NATO intervention and condemning the Arab League’s mediation attempts. He said that he did not have weapons, and nor did other people in the area, though he wished he did.

Syrian state media reported that security forces had “stormed dens of armed terrorist groups” in Idlib and the area of Daraa, seizing caches of weapons, ammunition, explosives and night goggles following clashes with the groups.