KABUL (Reuters) - Civilian casualties in Afghanistan rose to new highs in 2016, driven by more Islamic State attacks, the most deaths and injuries from air strikes since 2009 and a rising toll of child victims of unexploded ordnance, the United Nations said.

Afghan officials investigate at the site of a bomb blast near the U.S. Embassy in Kabul, Afghanistan August 15, 2016. REUTERS/Mohammad Ismail

A total of 3,498 civilians were killed in the conflict and 7,920 were wounded in 2016, a combined increase of 3 percent over the previous year, U.N. investigators said in an annual summary issued on Monday.

“Against a backdrop of protracted ground fighting, the battlefield permeated civilian sanctuaries that should be spared from harm, with suicide attacks in mosques; targeted attacks against district centers, bazaars and residential homes; and the use of schools and hospitals for military purposes,” the United Nations said.

About 61 percent of all civilian casualties were caused by anti-government groups like the Taliban and Islamic State, it said.

The United Nations attributed at least 4,953 deaths and injuries to the Taliban, but in a shift in 2016, investigators documented a 10-fold increase in casualties caused by Islamic State militants, who often target members of the Shiite Muslim minority.

At least 899 deaths and injuries were attributed to Islamic State, which has been a relatively minor faction in Afghanistan, but last year launched an increasing number of suicide attacks.

Last year saw the highest number of civilian casualties from suicide attacks since the United Nations began tracking such numbers in 2009.

Afghan security forces caused about 20 percent of the overall casualties, while pro-government militias and international forces caused 2 percent each.

Among the deadliest tactic used by government forces was the indiscriminate use of heavy weapons like mortars in populated areas, the United Nations said.

As the Afghan air force got more attack aircraft and the United States ramped up its air campaign against both Islamic State and the Taliban, casualties caused by air strikes increased 99 percent compared with 2015, hitting levels not seen since 2009.

Air strikes by international warplanes resulted in at least 127 civilian deaths and 108 injuries in 2016, while the Afghan air force accounted for at least 85 deaths and 167 injuries, the United Nations said.

Investigators were not able to attribute responsibility for 38 deaths and 65 injuries from air strikes.

U.S. officials have only acknowledged possible civilian casualties in one incident in Kunduz province in November, when the United Nations said as many as 32 noncombatants were killed and 26 wounded in a joint U.S.-Afghan raid.

Casualties among children spiked by 24 percent in 2016, with 923 dead and 2,589 wounded, largely as a result of a major increase in casualties from unexploded ordnance.