KABUL: The number of Afghan civilians killed in U.S. and NATO airstrikes dropped by nearly half last year to 126, the U.N. said Tuesday. The report came a day after President Hamid Karzai banned government forces from requesting foreign air support during operations in residential areas.

The overall civilian death toll in 2012 also declined some 12 percent to 2,754, compared with 3,131 the previous year, according to an annual report by the United Nations Mission to Afghanistan that tracks statistics in the 11-year-old war.

But while it was the first reduction in casualties in six years, the U.N. expressed concern about a spike in targeted killings and human rights abuses by armed groups, a worrisome trend as U.S. and other foreign troops prepare to withdraw combat troops by the end of 2014.

It also said the number of Afghan women and girls killed and injured in the conflict increased by 20 percent in 2012.

The report was released as anger is high over an airstrike last week in northeastern Kunar province that killed five children, four women and one man along with four insurgents. Angry that the strike was requested by his national intelligence service, Karzai on Monday ordered government troops to stop asking for foreign air support in residential areas.

The Taliban and other insurgents increasingly targeted civilians throughout the country and were responsible for 81 percent of the civilian casualties last year, the U.N. said. The report said that so-called anti-government elements killed 2,179 civilians and wounded 3,952, a 9 percent increase in casualties from 2011.

By contrast, the number blamed on U.S. and allied forces decreased by 46 percent, with 316 killed and 271 wounded in 2012.

The top U.N. envoy in Afghanistan, Jan Kubis, welcomed the decline in casualties but said "the human cost of the conflict remains unacceptable."

The Afghan Interior Ministry spokesman also said the decrease was a positive sign and pledged to do everything possible to stop the insurgents from attacking civilians.

"They're still using suicide bombers, they still use IEDs (roadside bombs) in the very populated areas and they still use civilians as a shield in the villages," Interior Ministry spokesman Sediq Sediqi said. "The important thing is that civilian should be decreased to zero."

The UNAMA report attributed the overall drop in civilian casualties to a decline in suicide attacks, reduced numbers of airstrikes and other measures taken by the U.S.-led coalition and the Afghan government.

It also cited "an unseasonably harsh winter which impeded insurgent movements and effects of earlier military operations against anti-government elements" and said the number of civilian casualties actually rose in the last half of the year.

Despite the decline, airstrikes remained the cause of most civilian deaths and injuries by the international military forces and 51 of those killed were children, the report said.

The death of civilians during military operations, particularly in airstrikes, has been among a major source of acrimony between Karzai's government and foreign forces.

The U.S.-led military coalition said last June that it would only use airstrikes as a self-defense weapon of last resort for troops and would avoid hitting structures that could house civilians. That announcement followed a bombardment that killed 18 civilians celebrating a wedding in eastern Logar province, which drew an apology from the American commander.

Afghans currently lead the majority of military operations nationwide and will fully take charge in the spring, a key step in the plan to withdraw U.S. and other foreign combat forces by the end of 2014. However, they remain heavily dependent on the coalition for air support and medical evacuations in areas where the Taliban and other militants live among the population and often enjoy local support.

The top U.S. commander in Afghanistan, Marine Gen. Joseph Dunford, said he believes the American-led NATO coalition can operate effectively despite the ban.