Civilian casualties in Afghanistan increased 23 percent  in the first six months of this year, the United Nations said in a report released Wednesday.

The rise in the number of ordinary Afghans killed and injured reverses a decline in 2012. That was the first drop in civilian casualties since the U.N. began publishing the figures in 2007.

The increase in deaths and injuries so far this year was mainly driven by the stepped up use of improvised explosive devices (IEDs), the United Nations Assistance Mission in Afghanistan said in its report.

Civilian deaths increased 14 percent  from the first six months of 2012 to 1,319, the report said, while injuries rose 28 percent  to 2,533.

"The violent impact of the conflict on Afghan civilians marked by the return of rising civilian casualties in 2013 demands even greater commitment and further efforts by parties to the conflict to better protect civilians who are increasingly being killed and injured in the cross-fire," said Jan Kubis, the U.N. secretary-general's special representative for Afghanistan.

Nearly three-quarters of all civilian casualties in the first half of the year resulted from actions by anti-government groups, notably the Taliban, the U.N. report found.

The remainder were caused by pro-government forces (9 percent ), ground engagements between pro- and anti-government forces (12 percent ) and unattributed factors like unexploded ordnance (5 percent ).

The report singled out the devastating effect of the use of IEDs, which caused 35 percent  of deaths and injuries. The devices killed 443 civilians and injured 917. That's a 34 percent  increase in overall casualties from the first half of 2012.

"The increase in the indiscriminate use of IEDs and the deliberate targeting of civilians by anti-government elements is particularly alarming and must stop," Kubis said.

The NATO-led International Security Assistance Force in Afghanistan welcomed the report, saying it had taken "a number of positive steps to reduce the number of civilian casualties in this country."

But the Taliban criticized the report, saying it was "in favor of Americans and part of the propaganda against the Taliban."

CNN's Brian Walker and Masoud Popalzai contributed to this report.