Russia on Friday blamed the "hasty withdrawal" of US and NATO troops for a rapid deterioration in Afghanistan's security and warned of instability spreading to neighbouring countries.

Taliban insurgents in Afghanistan have capitalised on the last stages of the withdrawal of foreign troops to launch offensives, capturing a swath of districts and border crossings, and encircling provincial capitals.

"In recent days we have unfortunately seen a rapid deterioration of the situation in Afghanistan," Russian Foreign Minister Sergei Lavrov said in comments carried by Russian news agencies.

"In light of the hasty withdrawal of the US and NATO troops, there is huge uncertainty around the future of the political and military situation in this country," he said at a conference in the Uzbek capital Tashkent.

Russia hosted Taliban representatives in Moscow last week, where the insurgent group claimed to have control over some 85 percent of Afghanistan.

Moscow is closely watching the Taliban's advance and concerned about the potential for instability reaching neighbouring Central Asian countries of the former Soviet Union where Russia maintains military bases.

Lavrov said the crisis had increased the threat of terrorism and worsened problems surrounding drug trafficking, which he said had reached "an unprecedented level".

"It's clear that, in this situation, there is a real risk of instability spreading to neighbouring countries," he said in Tashkent, according to the TASS news agency.

Earlier this week, ex-Soviet Tajikistan said nearly 350 Afghan refugees had crossed its border fleeing Taliban advances.

Tajikistan's President Emomali Rakhmon conducted inspections at border guard posts on Friday, having earlier called up 20,000 reservists to bolster defences along the country's shared border with Afghanistan.

Russia's defence ministry said this week it was staging military drills in Tajikistan where it has a base aimed at buttressing border security with Afghanistan.