Syrian government air raids on the city of Raqqa, which the Islamic State in Iraq and the Levant (ISIL) has proclaimed as its capital, have killed 135 people, activists have said.

Scores more people were reported to have been injured in the air strikes on Tuesday, which targeted a number of residential districts in the northern city.

The majority of the dead and injured are believed to be civilians, including women and children.

Local activists reported on Facebook that the Raqqa Red Crescent had transferred scores of bodies to the national hospital.

"Most of the casualties were caused by two consecutive air strikes targeting the city's industrial area," Rami Abdel Rahman, the director of the UK-based Syrian Observatory for Human Rights said.

"The first strike came, residents rushed to rescue the wounded, and then the second raid took place," said Abdel Rahman.

Raqqa is the only provincial capital to fall from government control since the outbreak of a 2011 uprising against President Bashar al-Assad.

The government has launched frequent air strikes against the city and other ISIL positions in northern and eastern Syria, but activists say most of the casualties have been civilians.

Syria's main opposition, the National Coalition, has issued a statement condemning the strikes, calling the attack on Raqqa a "heinous crime".

"There are many among the Syrians who now believe that the Assad regime is believed to be the sole benefactor of the US led coalition airstrikes and it is time to review the strategy against ISIL on the ground," the statement said. 

[Outside image courtesy of Aamaq News Agency]

Source: Al Jazeera and agencies