Public executions, amputations, lashings and mock crucifixion have become a regular fixture in jihadist-controlled areas of Syria, a UN-mandated probe charged Wednesday, also accusing Damascus of repeatedly using chemical weapons against civilians.

“In areas of Syria under (Islamic State) control, particularly in the north and northeast of the country, Fridays are regularly marked by executions, amputations and lashings in public squares,” the independent Commission of Inquiry on the human rights situation in Syria said.

Jihadists from the group now calling itself the Islamic State are also pushing residents, including children, to attend public executions by beheading or a shot to the head, it said.

“Executions in public spaces have become a common spectacle on Fridays in (IS power-base) Raqqa and in [IS]-controlled areas of Aleppo governorate,” said the commission, which includes legendary former war crimes prosecutor Carla del Ponte.

“Bodies of those killed are placed on display for several days, terrorizing the local population.”

In a 45-page report on the situation in the war-ravaged country, the panel described beheadings of boys as young as 15, men flogged for things like smoking or accompanying an “improperly dressed” female relative, and women publicly lashed for not following the group’s strict dress code.

IS, which declared a “caliphate” in an area stretching across northern Iraq and eastern Syria, is also recruiting and training children as young as 10, with teens being used in active combat and suicide-bombing missions, the report said.

The jihadists, who sparked worldwide outrage last week when they released a video showing its beheading of US journalist James Foley, are guilty of widespread war crimes and crimes against humanity in Syria, the commission said.

The group was also contributing “to a spillover of violence affecting international peace and stability,” it warned, stressing that “risks of the conflict spreading further are palpable.”

Damascus repeatedly used chemical agent

The commission was created three years ago by the UN Human Rights Council to investigate abuses committed in the war, which is estimated to have killed nearly 200,000 people.

It will present to the council next month its latest report covering a litany of war crimes and crimes against humanity it says were carried out by the Syrian government, IS and opposition groups.

The Syrian government, which during the first years of the conflict was blamed for the lion share of abuses and deaths, had since January continued to kill hundreds of men, women and children every week due to the “indiscriminate firing of missiles and barrel bombs into civilian areas,” the report found.

It also said Damascus appeared to have dropped barrel bombs containing the chemical agent chlorine on civilian areas in the north on eight different occasions last April.

“Reasonable grounds exist to believe that chemical agents, likely chlorine, were used on (northern Syrian villages) Kafr Zeita, al-Tamana and Tal Minnis in eight incidents within a 10-day period in April,” the report said.

“Witnesses saw helicopters drop barrel bombs and smelled a scent akin to domestic chlorine immediately following impact,” it pointed out.

Victims, it said, had suffered “symptoms compatible with exposure to chemical agents, namely vomiting, eye and skin irritation, choking and other respiratory problems.”

President Bashar Assad’s regime and rebels have both accused the other of using chemical agents, including chlorine, in the bloody uprising that began in March 2011 and in spite of Damascus promising to hand over all its chemical arms.

The Organisation for the Prohibition of Chemical Weapons (OPCW) mission also said in June that Damascus appeared to be using chlorine “in a systematic manner.”