Governments in the ex-Soviet region of Central Asia, where Moscow has strong relationships, have sounded the alarm over the spiral of conflict in neighbouring Afghanistan as US-led forces look to complete a withdrawal from Washington's longest ever conflict.

An AFP correspondent at the Kharb Maidon training ground in Tajikistan saw military helicopters and fighter jets soar overhead and tanks race in combat formation as troops from Russia, Tajikistan and Uzbekistan engaged in a simulation targeting an incursion from the south by extremists.

The week-long exercises followed smaller Russian-Uzbek drills held near Uzbekistan's border with Afghanistan that concluded last week.

Alexander Lapin, commander of Russia's Central Military District, told journalists 2,500-troop drills took place amid "increasing aggravation of the situation in Afghanistan and the threat of penetration by radical terrorist groups bordering the Central Asian countries".

The three militaries "achieved a high level of... direction and coordination," Lapin said of the manoeuvres that exacerbated a dust storm in the arid region.

The Central Military District said in a statement Tuesday the exercises had included new man-portable air-defence systems, handguns and assault rifles sent to upgrade Russia's military base in Tajikistan.

Lapin added that the joint drills were the first in the region to see military tactics employed by the Russian army in the conflict in Syria.

The Taliban has moved to reassure its Central Asian neighbours that it has no designs on the region which played a key logistical role when a coalition led by Washington forced the militant group from power two decades ago.

But Tajikistan in particular has raised concern over what its leader Emomali Rakhmon has called a build-up of "terrorist groups" near the frontier after the Taliban claimed control of key border posts in the north this summer.

Tajikistan's top defence official Sherali Mirzo said Tuesday the Islamic State group was among the "symbolic enemies" targeted in the war games.

As of Tuesday, the Taliban claimed to control six provincial capitals after a blitz across the north forced tens of thousands of people to flee their homes for the relative safety of Kabul and other centres.