Beirut: Activists have raised the death toll from a series of Syrian government airstrikes on the Islamic State group's stronghold in northeastern Syria to at least 95.

The strikes, which targeted Raqqa on Tuesday, also injured 'at least' 120 people, according to a monitoring group.

Some of the air raids struck a market near a museum and an industrial neighbourhood in the city, causing many civilian casualties.

The Britain-based Syrian Observatory for Human Rights raised its death toll Wednesday to 95.

Its director, Rami Abdurrahman, said they include 52 civilians whose names the group was able to document. Other activists estimated more than 100 people had been killed.

The Associated Press could not independently confirm the death toll - one of the worst single-day tolls in the city.