At least 36 civilians have been killed in air strikes by Syrian government warplanes on the Islamic State-held northern city of Raqqa, activists say.

Most of the casualties were caused by two strikes in quick succession on an industrial area, the UK-based Syrian Observatory for Human Rights reported.

One opposition activist network said more than 80 people had died.

Syrian government and US-led coalition aircraft frequently bomb Raqqa, which IS has made into a stronghold.

Activists say most of the casualties from the raids have been civilians.
Islamic State 'capital'

The Syrian Observatory said Tuesday's air raids had targeted a popular market near Raqqa's museum as well as the industrial area where two explosions caused most of the casualties.

"The first strike came, residents rushed to rescue the wounded, and then the second raid took place," the organisation's director, Rami Abdel Rahman, told the AFP news agency.

The Local Co-ordination Committees meanwhile said that a total of nine government air raids on Raqqa had left 87 people dead, including several children. Dozens of people were also wounded.

Another group called Raqqa is Being Silently Slaughtered said it had documented more than 70 deaths.

Raqqa is the only provincial capital to have been lost by the government since the uprising against President Bashar al-Assad began in 2011.

Western-backed and Islamist rebel groups fought for control of the city after seizing it in March 2013 before Islamic State ousted them in January.

The jihadist group made Raqqa the capital of the caliphate it proclaimed in June and governs it according to a strict interpretation of Islamic law.

The US and its Arab allies have been conducting air strikes on IS positions in Raqqa and elsewhere in northern and eastern Syria since September. An IS headquarters building outside Raqqa was targeted twice between Friday and Monday, according to the US military.

BBC