Beirut:A wave of Syrian regime air strikes on the Islamic State group`s self-proclaimed capital of Raqa, in the country`s east, killed at least 36 civilians on Tuesday, a monitor said.
"The death toll has risen to at least 36 in air raids on Raqa," said the Syrian Observatory for Human Rights, updating its earlier toll of at least 23 killed.
"Dozens more were wounded, some of them critically. We fear the death toll may rise further," Observatory director Rami Abdel Rahman told AFP.
The head of the Britain-based group said previously that "most of the casualties were caused by two consecutive air strikes" on Raqa`s main industrial zone.
"The first strike came, residents rushed to rescue the wounded, and then the second raid took place," said Abdel Rahman, whose group relies on a network of sources on the ground in Syria for its information.
The Islamic State organisation emerged in Syria`s war in spring 2013.
It took over Raqa, the only provincial capital to fall from government control since the outbreak of a 2011 revolt, and turned it into its bastion.
The government has launched frequent air strikes against Raqa and other IS positions in northern and eastern Syria, but activists say most of the casualties have been civilians.