At least 38 civilians have been killed in airstrikes conducted by the US-led coalition, purportedly fighting the Daesh Takfiri terrorist group, on the Syrian city of Raqqah in the past 48 hours, a pro-opposition monitoring group says.

The so-called Syrian Observatory for Human Rights said 17 people, including five children and two women, had been killed and 30 others injured in the airstrikes on the Old City neighborhood and other areas in the center of Raqqah on Wednesday.

The report said the latest casualties bring the number of people killed in such airstrikes in the past 48 hours to 38.

According to the Britain-based group, the death toll is expected to rise as several of the wounded are in critical condition and a number of people are still missing.

The observatory said the aerial attacks also damaged infrastructure.

The coalition has been conducting airstrikes against what are said to be Daesh targets inside Syria since September 2014, without any authorization from the Damascus government or a UN mandate.

The Western military alliance has repeatedly been accused of targeting and killing civilians. It has also been largely incapable of fulfilling its declared aim of destroying Daesh.

In July, the Pentagon admitted that the coalition airstrikes had killed over 600 civilians in Syria and Iraq between August 2014 and May 2017. Independent monitors, however, have time and again challenged such reports and revealed that the US-led campaign has caused far more civilian casualties.