The top US general in Afghanistan relinquished command on Monday at an official ceremony in the capital, the latest symbolic gesture bringing America's longest war nearer to its end.

At a time when the Taliban are making sweeping advances across the country, General Austin "Scott" Miller — the highest-ranked officer on the ground in Afghanistan — handed command to General Kenneth McKenzie, an AFP correspondent at the Kabul ceremony reported.

Miller has been in Afghanistan since 2018, but in May was charged by commander-in-chief President Joe Biden with organising the final withdrawal of US troops, to be completed by the end of August.

Since May, most of the 2,500 American troops remaining at that time have left, and the US has also handed over to Afghan forces Bagram Air Base, from where coalition forces carried out operations against the Taliban and extremist groups for the past two decades.

About 650 US service members are expected to be stationed in Kabul to guard Washington’s sprawling diplomatic compound, where Monday’s ceremony took place.

Top Afghan officials and military officers attended the ceremony inside the heavily fortified green zone.