WASHINGTON At least 600 civilians have been killed in strikes in Iraq and Syria by the U.S.-led coalition fighting Islamic State since the campaign began in 2014, according to a report released by the coalition on Friday.

The estimate in the monthly report, which said coalition strikes had unintentionally killed at least 603 civilians between August 2014 and May 2017, was far lower than figures provided by monitoring groups.

The monitoring group Airwars says a total of at least 4,354 civilians have been killed by coalition air strikes.

The latest coalition report included an incident on April 17 near the Syrian town of Abu Kamal, in which it said 25 civilians were killed and 40 were wounded during a strike against an Islamic State headquarters that caused a secondary explosion in the adjacent building.

Since the start of the campaign against Islamic State militants, the coalition has carried out nearly 22,000 strikes and has received 727 reports of potential civilian casualties, the report said.

The coalition, battling to defeat Islamic State militants in Iraq and Syria, says it goes to great lengths to avoid civilian casualties.

Ahead of a final assault on Raqqa city in Syria, the U.N. human rights office raised concerns about increasing reports of civilian deaths in the area. In a May report, it said there had already been “massive civilian casualties.”

In Mosul, the Iraqi military has forecast final victory this week in what used to be the de facto capital in Iraq of Islamic State’s self-declared caliphate, after an eight-month, U.S.-backed offensive to wrest back the city. Mosul’s pre-war population was 2 million.

(Reporting by Idrees Ali; Editing by Frances Kerry)