HERAT:-- Taliban fighters have reportedly killed or captured an entire Afghan National Armyinfo-icon company of more than 50 soldiers on Monday, Afghan officials said, the latest in a series of major attacks by the militant group even as it pursues a peace deal with the United Statesinfo-icon.

The attack, in which the Taliban were reported to have killed 16 soldiers and taken 40 prisoner, took place in northwestern Badghis Province, close to the country's western border with Turkmenistaninfo-icon. It came as Taliban negotiators entered a third week of talks with American diplomats in the Persian Gulfinfo-icon kingdom of Qatarinfo-icon.

In the assault, a large force of Taliban insurgents surrounded a base in the Bala Murghab district. After four hours of fighting, the militants captured or killed all of the soldiers in their base, as well as others at two outposts nearby, according to Abdul Aziz Beg, head of the Badghis provincial council.

The episode was the deadliest in a weeklong insurgent campaign that has killed, wounded or captured 70 soldiers in the district, Mr. Beg said. "The district is on the verge of collapse," Mr. Beg said. "The fighting has gone on for a week, but the government is not paying any attention."

Qais Mangal, a spokesman for the Afghan Ministry of Defense, confirmed the attack and said that four security outposts were captured by the Taliban. "We lost contact with all of the personnel there," he said. "We don't know the casualty figures."

Reinforcements, including commandos and air support, were deployed to the district as fighting continued, Mr. Mangal said.

The area has been the site of constant conflictinfo-icon for years, and the Taliban have made numerous efforts to take control of the district. The heavily mountainous area offers the promise of a border sanctuary for the insurgents.

Embedded rich media on Twitter

The attack came 10 days after a Taliban attack in southern Helmand Province in which 20 insurgents penetrated the defenses of an Afghan Army camp, killing as many as 40 soldiers. American forces stationed in the base helped to repel the Taliban attack.

On Monday, smaller Taliban attacks in Samangan, Sar-i-Pul, Balkh, Kunduz and Helmand Provinces were reported to have killed at least 13 members of the security forces. The casualties reflected the unusually high tempo of insurgent attacks during the winter months, when cold weather and snow blanket much of the country.

Afghan forces have been dying in record numbers. Last week alone, nearly 120 soldiers, police officers and pro-government militia members were killed in Taliban attacks across the country.

In January, President Ashraf Ghani, speaking at the Worldinfo-icon Economic Forum in Davos, Switzerlandinfo-icon, said 45,000 members of the security forces had died since he took office in September 2014 -- a much higher total than anyone in his government had previously acknowledged.