A UN report has said civilians are still the primary targets of fighting in Iraq, as Baghdad announces a large operation to push the Islamic State of Iraq and the Levant (ISIL) group out of Anbar province.

According to the annual report on the protection of civilians, most of the violence committed is by ISIL but said it is investigating reports of alleged abuses by Iraqi security forces and affiliated armed groups, including failure to protect civilians during air strikes and shelling.

A representative for the UN’s High Commissioner for Human Rights separately told Al Jazeera there was no evidence that barrel bombs, which are banned under international law, were being used by Iraq but that civilians appeared to be increasingly caught in government air strikes and artillery attacks on residential neighbourhoods where ISIL fighters were targeted.

The report said the UN mission to Iraq recorded at least 3,345 civilians killed and at least 7,423 wounded in fighting from December 2014 to the end of April this year. Most of the casualties were in Baghdad province, followed by Anbar and Diyala provinces.

“Armed groups affiliated to or supporting the Government also carried out targeted killings, including of captured fighters from ISIL and its associated armed groups, abductions of civilians, and destruction of property,” the report added.

Operations underway

Meanwhile, Iraqi troops backed by mainly Shia militias launched military operations on Monday to recapture the country's largest province Anbar from ISIL, a military statement broadcast on state television said.

The announcement of the offensive comes two months after the group seized Anbar's capital Ramadi, extending their control over the largely Sunni Muslim province west of Baghdad.

"At 5am this morning operations to liberate Anbar were launched," said a joint military command statement read out on state television.

It said the offensive was being carried out by the army, mainly Shia militia known as Hashd Shaabi (Popular Mobilisation) units, special forces, police and local Sunni Muslim tribal fighters.

The statement gave no other details, but military officers and Hashid Shaabi commanders have said the initial target will be the city of Falluja, about 50 km west of Baghdad.