The Syrian Network for Human Rights said armed groups and foreign fighters aligned with the government but not integrated into it were largely responsible for the sectarian violence.

Armed groups killed entire families, including women and children, during an outbreak of sectarian violence in Syria last week, the United Nations human rights office said on Tuesday.

Syria's fragile transition from decades of Assad family brutal rule has been greatly shaken with an outburst of sectarian retribution and killings, posing a serious challenge to the new leadership led by Ahmad Sharaa.