KABUL, Afghanistan — The number of civilians killed by Afghan and American airstrikes is rising, the United Nations said Tuesday, as the Afghan government increasingly relies on airpower in its fight against a resurgent Taliban.

The United Nations mission in Afghanistan said 21 civilians were killed in two airstrikes last weekend and urged all parties to the conflict to take stronger measures to protect civilians.

After the release of the United Nations statement, an airstrike on Tuesday in the Chardara district of Kunduz Province killed three more people, a 45-year-old woman and two teenage girls, according to Sher Mohammed, the husband of the woman who died.

On Wednesday, angry residents carried the bodies of two of the victims to the city of Kunduz, the provincial capital, and chanted slogans against the government and American forces.