At least 3,812 Afghan civilians were killed or wounded in the first half of 2019 in the war against militant groups, including a big increase in the number of casualties caused by government and NATO-led troops, the United Nations said on Tuesday.

The latest casualty figures were released as talks between the Taliban and U.S officials to end the 18-year Afghan war entered an important stage, with U.S. negotiators aiming to reach a peace deal before Sept. 1.

However, the war has raged on despite the diplomatic efforts, forcing civilians to live under the constant threat of being targeted by militants or being caught up in ground fighting, or becoming inadvertent victims of air strikes by Afghan government and NATO-led forces.

The U.N. Assistance Mission in Afghanistan (UNAMA) said in its latest report ground raids and clashes caused the most civilian casualties, followed by bomb attacks and air strikes. The figures show a 27% drop in casualties for the first half of 2019 compared to the same period last year, which was a record, but nonetheless, 1,366 civilians were killed and another 2,446 injured.

While the U.N. welcomed the decrease, it "continues to regard the level of harm done to civilians as shocking and unacceptable," UNAMA said in a statement.

The agency "acknowledges that parties have announced efforts to reduce civilian casualties, but they are insufficient."

Taliban and Daesh fighters killed 531 Afghans and wounded 1,437 between Jan. 1 and June 30. The terrorist groups deliberately targeted 985 civilians, including government officials, tribal elders, aid workers, and religious scholars, UNAMA said in its report.

It said pro-government forces including international troops killed 717 Afghans and wounded 680 in the six months to June 30, a 31% increase from the corresponding period in 2018.

At least 144 women and 327 children were killed and more than 1,000 wounded across the country.

Air strikes caused 519 civilian casualties, 150 of whom were children.

"Parties to the conflict may give differing explanations for recent trends, each designed to justify their own military tactics," UNAMA human rights chief Richard Bennett said.

"The fact remains that only a determined effort to avoid civilian harm, not just by abiding by international humanitarian law but also by reducing the intensity of the fighting, will decrease the suffering of civilian Afghans," he said.

U.S. and other NATO troops are stationed in Afghanistan as part of a mission to train, assist and advise Afghan forces and to carry out counter-terrorism operations.

Colonel Sonny Leggett, a spokesman for U.S. forces in Afghanistan, rejected the methods and findings used by UNAMA, saying the collection of evidence by U.S. forces was "more thorough, evidentiary and accurate".

Leggett, however, did not give any U.S. military figures for civilian casualties but said U.S. forces worked closely with Afghan security forces to prevent them.

"We follow the highest standards of accuracy and accountability and always work to avoid harm to civilian non-combatants," Leggett said.

Afghanistan's bloody death toll is climbing amid a months-long, U.S.-led push to forge a peace deal with the Taliban that would see foreign forces quit the country in return for various security guarantees. U.S. President Donald Trump wants combat forces reduced in Afghanistan by the next presidential election, U.S. Secretary of State Mike Pompeo said on Monday, in comments that underlined the growing pressure from Washington to cut troop numbers there.

Trump's South Asia strategy, unveiled in August 2017, called for an open-ended deployment of U.S. forces with the goal of compelling the Taliban to negotiate peace with the Kabul government to end nearly 18 years of war.

However, Pompeo's comments underscored a shift that has apparently taken place since talks with the Taliban opened last year.

Pompeo's comments came at a delicate moment, as Afghanistan prepares for a presidential election of its own in September and the U.S. prepares to engage in another round of talks with the insurgents. Earlier this month as part of that effort, Taliban officials met at a historic summit with Afghan representatives at an "intra-Afghan dialogue" in Doha.