The latest information from the UN Assistance Mission in Afghanistan (UNAMA) shows a 27 percent 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 UN 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."

UNAMA also said that for the second quarter running, US and pro-government forces caused more civilian deaths than the Taliban and other insurgent groups.

During the first half of 2019 pro-government forces, including the US, killed 717 civilians, an increase of 31 percent from a year earlier.

Most of the deaths came from US and Afghan air strikes, often in support of national forces on the ground.

Colonel Sonny Leggett, spokesman for US Forces-Afghanistan, disputed UNAMA's data and said the US military investigates all civilian casualty allegations in what is a "complex environment".

"USFOR-A rejects UNAMA's methods and findings. Sources with limited information and conflicted motives are not always credible," Leggett said in a statement.

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

Afghanistan's bloody toll is climbing amid a months-long, US-led push to forge a peace deal with the Taliban that would see foreign forces quit the country in return for various security guarantees.

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.

Delegates issued a vague resolution that included a pledge to reduce civilian casualties to "zero", but in the weeks since, ordinary Afghans have continued to be killed and wounded.

"Everyone heard the message loud and clear from Afghan delegates in the Doha talks -- 'reduce civilian casualties to zero!'" UNAMA head Tadamichi Yamamoto said in a statement.

"We urge all parties to heed this imperative, to answer the call of Afghans for immediate steps to be taken to reduce the terrible harm being inflicted."

Child casualties represented almost one-third of the overall total of civilian casualties, with 327 deaths and 880 injured, UNAMA said.

A UN tally found last year was the deadliest on record, with at least 3,804 civilian deaths caused by the war -- including 927 children.