BEIRUT (REUTERS) - Air raids killed scores of people over the past 24 hours in the provinces of Raqqa and Deir al-Zor in northern and eastern Syria, which are mostly controlled by Islamic State in Iraq and Syria (ISIS) militants, a monitoring group said on Saturday.

Air strikes carried out by Russian or Syrian warplanes killed at least 29 people in the town of Khasham near the city of Deir al-Zor on Saturday, the Britain-based Syrian Observatory for Human Rights said.

The death toll in two other towns near Deir al-Zor reached 44, in strikes also carried out by Russian or Syrian warplanes the day before, it said.

In Raqqa city, ISIS' de facto capital in Syria, at least 32 people were killed.

Russian jets have been bombing around Deir al-Zor as Syrian pro-government forces clash with ISIS fighters, who control most of the province. The group has besieged remaining government-held areas of the city since last March and last week launched new attacks.

In Raqqa, Russian warplanes have been bombarding ISIS positions.

Jets from a US-led coalition have separately struck the group in both Raqqa and Deir al-Zor provinces.

The United States says most of Russia's air strikes in support of Syrian President Bashar al-Assad are targeting other rebel groups in the west of the country, including foreign-backed fighters.