The Britain-based Syrian Observatory for Human Rights says the strikes on the village of Susa in Deir Ezzor province were likely conducted by the US-led coalition.
Air strikes on one of the last villages still held by Daesh in eastern Syria killed 12 civilians, including four children, a war monitor said on Monday.
The strikes were carried out late on Sunday on the village of Susa in Deir Ezzor province, the Syrian Observatory for Human Rights said.
"Twelve civilians from a same family, including four children, were killed," Observatory head Rami Abdel Rahman said.
#SOHR A #massacre of 12 citizens from one family in one of the 5 remaining towns and villages controlled by the “#IslamicState” organization in the eastern banks of #Euphrates River https://t.co/TRLaGr443T— #المرصدالسوري #SOHR (@syriahr) January 1, 2018
The Britain-based monitoring organisation, which has a broad network of sources on the ground, said the strikes were likely conducted by the US-led coalition that launched air raids against Daesh in Syria and Iraq in 2014.
There was no immediate comment from the coalition.But the civilian death toll announced by the coalition is usually much lower than figures provided by independent war monitors.
Daesh has lost nearly all the territory it once held in Iraq and Syria and is clinging to a scattering of small villages and pockets of land in the border area.
The coalition admitted on Thursday to "unintentionally" killing at least 817 civilians since it started its aerial campaign against Daesh.
The civilian death toll provided by the US-led coalition are usually far lower than figures provided by independent monitors.
Clashes claim 52 civilian lives in Idlib in one week
At least 52 civilians, including 12 children and 12 women, were killed during clashes between regime forces and rebels belonging to a former Al Qaeda-affiliated group in Idlib province in a week, according to the Syrian Observatory for Human Rights.
During the attacks almost 110 civilians were also injured.
The death toll is expected to increase since the condition of many injured people is critical, the war monitor added.
The clashes between regime forces and former Al Qaeda affiliated rebels have continued in the southern countryside of Idlib province and eastern countryside of Hama province.
Regime forces first aim to take control of the southeast of Idlib province, Observatory head Rami Abdel Rahman said.
This would allow the regime to have full control of a road that links the capital Damascus to the regime-held second city of Aleppo.