The United States-led NATO mission in Afghanistan is withholding key information about Taliban attacks, a US government watchdog has said, potentially making insights into the war harder just as the Pentagon begins withdrawing its troops, EDNews.net reports citing Aljazeera.

The Resolute Support (RS) mission previously disclosed data on "enemy-initiated attacks", one of the few remaining public metrics of the conflict and the strength of the Taliban and other armed groups.

In its quarterly report released on Friday, the office of the Special Inspector General for Afghanistan Reconstruction (SIGAR) said the RS had stopped providing numbers.

Instead, the NATO mission gave only a short statement noting the Taliban stepped up attacks in March, immediately after the signing of a US-Taliban deal that was supposed to pave the way for peace talks.

"Between March 1 and 31, the Taliban refrained from attacks against coalition forces; however they increased attacks against (Afghan forces) to levels above seasonal norms," the RS said, according to the report.

Under the deal, foreign forces will quit Afghanistan by July 2021 if the Taliban starts peace talks with Kabul and sticks to various security commitments.

In the week before the February 29 deal signing in the Qatari capital Doha, violence plummeted during a partial truce and US officials hoped attacks would stay low.