The death toll from an attack on a camp for internally displaced people near the town of Sarmada included women and children, the Syrian Observatory for Human Rights said, and could rise further because many people were seriously wounded.
U.N. human rights chief said initial reports suggested a government plane was responsible.
U.N. High Commissioner for Human Rights Zeid Ra’ad al Hussein said the attacks were almost certainly a deliberate war crime.
“Given these tent settlements have been in these locations for several weeks, and can be clearly viewed from the air, it is extremely unlikely that these murderous attacks were an accident,” Zeid said in a statement.
“My staff, along with other organizations, will leave no stone unturned in their efforts to research and record evidence of what appears to be a particularly despicable and calculated crime against an extremely vulnerable group of people,” he said.
“Initial reports suggest the attacks were carried out by Syrian Government aircraft, but this remains to be verified.”
Footage shared on social media showed rescue workers putting out fires which still burned among charred tent frames, pitched in a muddy field. White smoke billowed from smoldering ashes, and a burned and bloodied torso could be seen.
 

A fireman douses burnt tents at a camp for internally displaced people near Sarmada in Syria’s Idlib province .

Sarmada lies about 30 km (20 miles) west of Aleppo, where a cessation of hostilities brokered by Russia and the United States had brought a measure of relief on Thursday.
Zeid said most of the people in the camps had been forced to flee their homes in Aleppo in February because of sustained aerial attacks there.
He said he was also alarmed about the situation in Syria’s Hama central prison, where detainees had taken control of a section of the prison and were holding some guards hostage.
“Heavily armed security forces are surrounding the prison and we fear that a possibly lethal assault is imminent. Hundreds of lives are at stake, and I call on the authorities to resort to mediation, or other alternatives to force,” Zeid said.
He urged governments on the U.N. Security Council to refer Syria to the International Criminal Court so that there is “a clear path to punishment for those who commit crimes like these”.
The bombing of a Syrian refugee camp that left dozens of civilians dead and wounded and was blamed on the government of Bashar al-Assad was “despicable” and “could amount to a war crime”, senior UN figures have said.
 

Stephen O’Brien, the UN under-secretary general for humanitarian affairs, demanded an immediate investigation. “If this obscene attack is found to be a deliberate targeting of a civilian structure, it could amount to a war crime,” he said.
The White House earlier called the strike indefensible. There was no justifiable excuse to target civilians who had already fled their homes from violence, White House spokesman Josh Earnest said, calling the situation heartbreaking.
The opposition’s Syrian National Coalition described the attack as an “appalling massacre by regime forces against civilians” and said it showed Assad was not a serious partner for peace. “The Syrian Coalition condemns the international community’s silence, which represents direct complicity in Assad’s war against civilians in Syria as it has been interpreted by the regime as a green light to kill more and more Syrians,” the coalition said in a statement, adding that more than 30 people were killed in the attack and dozens were injured.
Médecins sans Frontières (MSF), which operates a camp for 80,000 internally displaced Syrians in nearby Atmeh and had provided vaccinations to the refugees in al-Kammouneh, said the attack showed that civilians were paying the price for the ongoing conflict. The charity said it did not know exactly what happened in the attack on the camp, or who was responsible, but that the camp was inhabited by internal refugees who had already been displaced multiple times during the war.
“It is extremely concerning … and a clear sign again that civilians are paying the price in this conflict,” said Sam Taylor, MSF’s communications coordinator for Syria.

Source: Reuters, Guardian, 6 May 2016