DHAKA: The Islamic State group has executed 700 members of a tribe it has been battling in eastern Syria during the past two weeks, the majority of them civilians.

The killing spree happened in several villages inhabited by the al-Sheitat tribe in Deir Ezzor province, where the tribe are from, the Syrian Observatory for Human Rights group said on Saturday.  

The Observatory said many of the victims, who were Sheitat tribesmen, were beheaded after they were captured by the Islamic State group, reports al-jazeera.

Among the members of the Sheitat tribe killed were 100 fighters, but the rest were civilians, the activist group, which opposes Syrian President Bashar al-Assad, said.

The men were killed in the Ghranij, Abu Hamam and Kashkiyeh villages of the mainly IS-controlled province of Deir Ezzor, according to the Observatory, which relies on a vast network of activists and medics on the ground for its information.

Observatory head, Rami Abdel Rahman, said that the fate of 1,800 other members of the tribe was unknown.

On Saturday, the opposition Syrian National Council (SNC) called on the United States and its allies to conduct air strikes in Syria against the Islamic State group, similar to those being carried out against the same group's positions in neighbouring Iraq. 

BDST: 0858 HRS, AUG 17, 2014