US-led air strikes in Iraq and Syria have killed another 50 civilians, the international coalition against the Islamic State group announced on Friday.

With the latest deaths, "at least 735 civilians have been unintentionally killed by coalition strikes," it said in a statement, without specifying when the deaths occurred.

The United States began carrying out strikes against IS in Iraq in August 2014, a campaign that has since been expanded to Syria and now includes dozens of countries backing counterterrorism efforts.

The strikes have played a key role in a series of successful operations to push IS back in Iraq and Syria, but have taken a deadly toll on non-combatants caught up in the fighting.

Iraqi forces launched an assault on IS-held Hawijah on Friday that a top commander said marked the second phase of an operation launched earlier this month that aims to retake it and the nearby towns of Al-Abbasi, Riyadh and Rashad.

All are mainly Sunni Arab towns that have long been bastions of insurgency and were bypassed by government forces in their push north on second city Mosul last year that culminated in the jihadists' defeat in their most emblematic stronghold this July.

In Syria, IS is facing rival offensives by US-backed fighters and Russian-backed government forces.

The jihadists launched a major counteroffensive against government forces on Thursday, killing at least 73 troops and militia in a series of attacks along their supply lines, the Syrian Observatory for Human Rights said.

source: AFP