An Afghan official briefed on the matter put the number of casualties last year at close to 16,000 soldiers and police officers, with more than 5,000 killed. Even those numbers seemed low, considering that 4,100 were killed in the first six months of 2015, and the fighting greatly intensified in the last six months of the year.

Gen. Dawlat Waziri, a spokesman for the Afghan Defense Ministry, declined to specify the number of soldiers killed. He referred to the ministry’s daily news releases, which often include reports of the day’s casualties.

“All I can say is that compared to 2014, the casualties in 2015 were more,” General Waziri said.

In the district of Deh Rawood in southern Oruzgan Province, where the police have long complained of a lack of equipment and ammunition while practically under siege, four security checkpoints were abandoned by the police and later burned down by the Taliban, according to Mohammad Karim Khadimzai, head of the Oruzgan provincial council. Around 30 police officers deserted their posts in Deh Rawood and arrived in Tirin Kot, the provincial capital.

“The reason for deserting their posts, the police said, is a lack of ammunition despite frequently asking headquarters for supplies,” Mr. Khadimzai said.

But the provincial police chief has rejected that claim, saying the reason for the officers’ desertion was that the post’s commander had been fired recently over complaints from local residents that he had mistreated them. The provincial chief said the police officers who had deserted their posts were under investigation.

Dost Mohammad Nayab, a spokesman for the provincial governor, denied that the posts had been burned down by the Taliban, and said new forces had arrived to fill the vacuum.

The recent increase in urban attacks by the Taliban, in addition to a territory-gobbling offensive across the country, has coincided with international efforts to restart peace talks between the insurgents and the Afghan government. After a brief surge of progress last year, the effort stalled in July after it was revealed that the Taliban’s leader, Mullah Muhammad Omar, had died in 2013.

Officials from Afghanistan, China, Pakistan and the United States are expected to meet for a third time soon to discuss a plan to bring the Taliban to the negotiating table.