KANDAHAR, Afghanistan — Local Afghan officials are blaming the American military for two airstrikes that killed 29 people this week, most of them women and children, in heavy fighting in southern Helmand Province, even as American diplomats negotiated possible peace terms with the Taliban.

The reaction followed a familiar pattern in the long history of disputed airstrikes in Afghanistan, with the American military denying that the second airstrike even occurred, while confirming that the first was under investigation. The United Nations called the civilian casualty reports “credible.”

In Doha, Qatar, where the American peace envoy Zalmay Khalilzad was in the fifth day of peace negotiations on Friday, Taliban negotiators accused the American military of stepping up airstrikes to pressure them to make a deal.

“Killing innocent people, with their women and children, is a great concern to us,” said a senior member of the Taliban reached by telephone in Pakistan. “We raised the issue with Khalilzad.”