Human rights activists say Syrian forces have killed at least 20 people during anti-government protests around the country, as the government faces new accusations that it may be guilty of “crimes against humanity.”

The Syrian Observatory for Human Rights says most of Friday's casualties occurred in the Homs region. Security forces have launched a series of raids in the city in search of dissidents, and activists said Syrian soldiers also were killed in an apparent ambush.

The casualty figures could not be independently verified because Syria bars most foreign journalists from operating in the country.

The fresh violence coincides with the Friday release of a Human Rights Watch report, saying Syrian authorities may be guilty of crimes against humanity for alleged torture and unlawful killings.

Human rights groups and opposition leaders have urged the demonstrators to call for a suspension of Syria's Arab League membership. The 22-member league will hold an emergency meeting in Cairo on Saturday to discuss Syria's unrest.

That meeting follows an apparent breakdown of the Arab-League brokered agreement that calls on the Syrian government to end its brutal crackdown on dissent.

Earlier this month, Syria announced that it had agreed to the plan, which includes a withdrawal of security forces from the streets and talks with the opposition. Activists and witnesses, however, have reported continued violence.

On Thursday, Amnesty International called on the Arab League to press Syria to allow independent monitors to enter the country.

Earlier in the week, the U.N. human rights office said at least 3,500 people had been killed in the country since protests against Syrian President Bashar al-Assad began in March.