Rights activists said Wednesday that the death toll from violence in the central city of Hama is at least 22 after Syrian security forces opened fire on civilians.

Activists say that more than 50 people were wounded during an assault Tuesday when forces that had surrounded the city pushed through improvised barriers and roadblocks set up by Hama residents after massive anti-government protests.

Activists say forces also entered northwest Idlib province on Tuesday, apparently as part of the government's widening crackdown on dissent.

Amnesty International said Wednesday that Syrian forces may have committed crimes against humanity during an operation last month near the Lebanese border.

The London-based rights group accuses Syria of rounding up scores of male residents in the town of Talkalakh and torturing most of them. It quotes witnesses who say at least nine people died in custody.

Amnesty International says the action appeared to be part of a “widespread, systematic attack against the civilian population” that constitute crimes against humanity. It urged the U.N. Security Council to refer the situation in Syria to the International Criminal Court.

Rights groups say Syrian security forces have killed at least 1,400 civilians since mid-March while trying to suppress the anti-government uprising. The Syrian government says terrorists and Islamist militants have killed hundreds of security personnel during the same period.