KANDAHAR, Afghanistan — Besieged Afghan officials in the southern province of Oruzgan said on Sunday that scores of regular Afghan soldiers had surrendered in the past week to the Taliban, a trend also occurring recently in other provinces.

The latest case involved 41 Afghan National Army soldiers who surrendered and turned their base, the Mashal base in Chora District, over to the insurgents on Saturday night, according to Dost Mohammad Nayab, the spokesman for the province’s governor.

He said it was the third Afghan Army post in the province to surrender to the Taliban in the past week. Significant surrenders have been reported in Kunduz and Helmand Provinces as well.

The Taliban have taken more territory in Afghanistan this year than at any time in their 15-year struggle against the Western-supported Afghan government, according to United Nations data. At the same time, the Afghan military has suffered declining numbers and high attrition rates, according to data from the United States military. Afghan officials have said military casualty rates are historically high.