The London-based Syrian Observatory for Human Rights (SOHR) says the death toll from a suspected US-led coalition air strike near the Iraqi border has risen to 42 and will likely continue to rise.
On Tuesday, SOHR said that 11 children and 6 women were among the fatalities in the border town of Al Bokamal.
It said the fatality list included at least 14 Iraqi refugees.
The US-led coalition has not yet commented on this report.
But earlier in May the Pentagon said that its investigations had revealed that more than 350 civilians had been mistakenly killed in air strikes by coalition forces in Iraq and Syria.
On March 17, US coaliton fighter jets bombed a residential area of Mosul in pursuit of an ISIS truck bomb.
At least 200 civilians were killed, with some saying fatalities were as high as 400.
The Washington Post a week later called it “potentially one of the worst U.S.-led civilian bombings in 25 years”.
The SOHR report comes as UN Special Envoy to Syria Staffan de Mistura convenes the sixth round of peace talks in Geneva.
Mistura has told reporters that the Geneva talks are “in tandem” with the peace conference held in Astana, Kazakhstan in early May.
During the Astana talks, Iran, Russia and Turkey sponsored a Memorandum of De-Escalation for establishing four safe zones which the Russian news agency TASS said include “the Idlib province and some neighboring territories (Latakia, Hama and Aleppo) to the north of Homs, East Ghouta and some provinces in southern Syria (Daraa and Quneitra)”.
The current round of Geneva talks will benefit from a new format, de Mistura says.
He pointed to four working points for discussion and negotiation, which include holding negotiations, a new constitution, reformed governance and anti-terrorisim efforts.
Syrian President Bashar Al Assad has played down the relevance of the Geneva talks but has nonetheless sent a delegation of 18 senior officials and diplomats.
The armed Syrian opposition says it hopes that the Geneva round of talks will produce a comprehensive ceasefire.
The BRICS Post with inputs from Agencies