The Islamic State had in just a couple of months executed at least 116 foreign fighters who wanted to quit jihad and return home, Reuters cited a UK-based human rights monitoring group as saying.
According to the Syrian Observatory for Human Rights, the men killed were foreign fighters who had joined the insurgency but were in the act of leaving militant controlled territory.
However, the monitoring group warned that the numbers were probably underestimates. 'We believe that the real number of people that had been killed by IS is higher than the number documented,' it said on its web site.
The group which enforces an extreme version of religious law on the areas it controls had killed at least 1,878 people in six months, including those who tried to escape.
The militant group had taken huge areas of Iraq and Syria and declared a caliphate in territory under its control in June. The group had since then fought the Syrian and Iraqi governments, other insurgents and Kurdish forces.
According to Rami Abdulrahman, the head of the Syrian monitoring group, who spoke to Reuters, the Islamic State had killed at least 1,175 civilians, including eight women and four children.
He added that 930 of the civilians were members of the Sheitaat, a Sunni Muslim tribe from eastern Syria which fought Islamic State for control of two oilfields in August.
Meanwhile, www.rferl.org reported the observatory as making a statement on 28 December that it had documented the executions of nearly 1,200 civilians who were shot, stabbed, or beheaded by the extremist group since June, mainly in the provinces of Deir al-Zour, Al Raqqa, Hama, Aleppo, and al-Hasaka. The report was based on reporting by AFP, DPA and trend.az.
IS militants also executed some 500 Syrian soldiers and around 100 members of other Islamic groups fighting in Syria.
Meanwhile, the US Central Command reported yesterday that eight coalition air strikes on the Kobani area in northern Syria had destroyed 13 IS fighting positions and hit one large IS unit.
According to the Central Command coalition forces in Iraq launched five air strikes, one each near Sinjar and Mosul that destroyed IS fighting positions, two at IS facilities near Al-Qaim, and one near Ar-Rutbah that destroyed an IS bunker and vehicle.