Damascus, Aug 18 (IANS): A total of 31 radical fighters were killed as the Syrian air force Sunday struck positions of the Islamic State (IS) militants in the country's Raqqa province, the Syrian Observatory for Human Rights, a Britain-based watchdog group, said.

The 31 rebels were killed as a result of a series of air strikes the Syrian air forces carried out against the IS positions in Raqqa, which has fallen to the IS militants except for the al- Tabaqa military airbase, Xinhua reported.

The Observatory, which relies on a network of activists on ground, said eight civilians, including a child, were also killed as a result of the air strikes.

The stepped-up attack by the Syrian army came a day after the IS fighters were said to have killed as high as 700 tribesmen in Syria's Deir al-Zour province over the past two weeks.

The IS, previously known as the Islamic State in Iraq and the Levant (ISIL), has recently proclaimed the establishment of an " Islamic Caliphate" straddling Syria and Iraq, and changed its name into the "Islamic State".

The group led by Abu Bakr al-Baghdadi, who commands tens of thousands of fighters, said their goal is to establish an Islamic state in Iraq and Syria to fight the Shiite government of Iraqi Prime Minister Nouri al-Maliki and that of Syrian President Bashar al-Assad.

Syria has been gripped by deadly conflict since March 2011. Over 160,000 people have reportedly been killed and millions displaced due to the violence.