September 'deadliest month for Syrians' in 2017

September was the deadliest month for Syrians this year, a human rights observatory said on Sunday, following intense bombardments of Idlib and Islamic State group-occupied territories in October.

The ongoing war in Syria has killed at least 3,000 people including 955 civilians in September, the Syrian Observatory for Human Rights monitor said.

"More than 70 percent of the civilians were killed in regime and Russian air strikes, or in air raids of the international coalition" fighting Islamic State group, the Britain-based watchdog's head Rami Abdel Rahman said.

Backed by Russian air strikes, the forces of Syria's President Bashar Assad - notorious for their indiscriminate targeting of civilians - are pressing a battle to retake IS-controlled areas in the eastern province of Deir az-Zour.

A US-led international coalition has been providing air support to a Kurdish-Arab alliance also fighting the militants in its former northern bastion of Raqqa city and Deir az-Zour.

The number of people killed in September was higher due to increased fighting and "intensified air raids of the international coalition and Russia against militant bastions in the north and east of Syria, but also due to increased Russian and regime strikes on rebel-held areas," Abdel Rahman said.

The 955 civilians killed in September included 207 children, said the Observatory, which relies on a wide network of sources inside Syria for its information.

It said 738 militants - mostly from IS and a group led by al-Qaeda's former Syria affiliate - also died.

The Syrian conflict began when the Baath regime - in power since 1963 and led by Assad - responded with military force to peaceful protests demanding democratic reforms during the Arab Spring wave of uprisings.

It triggering an armed rebellion fuelled by mass defections from the Syrian army.

According to independent monitors, hundreds of thousands of civilians have been killed in the war, mostly by the regime and its powerful allies.

Millions more have been displaced both inside and outside of Syria.

The brutal tactics pursued mainly by the regime - which have included the use of chemical weapons, sieges, mass executions and torture against civilians - have led to war crimes investigations.