At least 352 civilians have been killed in US-led strikes against Isis targets in Iraq and Syria since operations began in 2014, the Pentagon has said.

Axar.az reports citing AP and Reuters.

The Combined Joint Task Force, in its monthly assessment of civilian casualties from the US coalition's operations against the jihadi group, said it was still assessing 42 reports of civilian deaths.

It added that 45 civilians were killed between November 2016 and March 2017. It reported 80 civilian deaths from August 2014 to the present that had not previously been announced. The report included 26 deaths from three separate strikes in March.

The military's official tally is far below those of other outside groups. Monitoring group Airwars said more than 3,000 civilians have been killed by coalition air strikes.

Included in Sunday's tally were 14 civilians killed by a strike in March that set off a secondary explosion, as well as 10 civilians who were killed in a strike on Isis headquarters in the same month.

“We regret the unintentional loss of civilian lives ... and express our deepest sympathies to the families and others affected by these strikes,” the Pentagon said in a statement.

The report did not include findings from an ongoing investigation into a 17 March strike targeting Isis fighters in the Iraqi city of Mosul. That strike resulted in more than 100 civilian deaths, according to reports from residents. Last month, the U.S. acknowledged coalition planes conducted a strike “at the location corresponding to allegations of civilian casualties,” but did not confirm the reports of high civilian casualties.

Coalition officials have declined to give a time frame as to when the investigation into the incident will be complete.

The US began the campaign of air strikes against Isis in 2014 after the extremists pushed into Iraq from Syria, overrunning Mosul and large swaths of Iraq's north and west. Since then Iraqi forces have slowly clawed back territory. Now a cluster of western Mosul neighbourhoods are the last significant urban terrain under Isis control in Iraq.