US military admits killing two dozen Syrian civilians in July airstrike .

The US military has admitted culpability for killing approximately two dozen civilians in a July airstrike outside the Syrian city of Manbij, then the scene of fierce fighting with Islamic State militants.

By the Pentagon’s account, the strike, which hit the Syrian village of Tokhar near Manbij, represents the single worst incidence of civilian casualties in the entire US war against Isis. But human rights monitors believe the US military is still undercounting the death toll, which is substantially lower than the ranges those monitors have compiled.

The Syrian Network for Human Rights has listed, mostly by name, 98 men, women and children dead from the July airstrike. The human-rights monitor Airwars, based in the UK, assesses civilian deaths in the strike to range between 73 and 203.

In a statement on Thursday, US central command (Centcom), said that an internal investigation had concluded that “up to 24” civilians died from the bombing.

Key details of the incident remain unclear: the attack at Tokhar, near Manbij, occurred in the early morning hours of 19 July, local time. Centcom listed the date of the strike as 18 July, while saying that a different 19 July strike allegation, this one near Aleppo, did not in fact happen. But it had previously acknowledged that the airstrike in question occurred.

Centcom said the civilian deaths resulted from Isis “interspers[ing]” civilians with its fighters at an area identified as a staging ground for a “counterattack” against US and proxy forces.

At the time, the two sides had been locked in weeks of fierce fighting for control of Manbij, a waypoint for Isis to exfiltrate terrorists through Turkey, and – for the US coalition – the last obstacle southward to Isis’ Syrian capital of Raqqa.

The US said the airstrike targeted the area and “inadvertently” killed the non-combatants alongside nearly 100 Isis militants.

“Unknown to Coalition planners, civilians were moving around within the military staging area, even as other civilians in the nearby village had departed over the previous days,” Centcom said in its statement.

After various investigations into allegations of US-caused casualties, Centcom now believes that the US has inadvertently killed 173 people to date in a war that has entered its third year.

But monitoring groups say that the US has systematically undercounted the civilian death toll of the war.

“Our own research indicates at least 330 civilians died in these same events. Even when [Centcom] confirmed cases, there appears to be under-reporting on these incidents,” said Airwars’ Chris Woods.

Woods said he was “very pleased” that Centcom acknowledged its role in the Manbij-area strike, though he noted the confusion in dates as to when the strike occurred. But he considered the variance in casualty figures alarming.

“How can we only have 24 killed by the coalition, when we have such substantial reporting of civilian casualties that day?” said Woods.