NATO Secretary-General Jens Stoltenberg has warned the alliance could pay a heavy price for withdrawing troops from Afghanistan "too soon".

Axar.az reports citing foreign media that it comes after a US official said President Donald Trump is expected to bring home a considerable number of American troops in the coming weeks.

Mr Stoltenberg said: "We now face a difficult decision. We have been in Afghanistan for almost 20 years, and no NATO ally wants to stay any longer than necessary.

"But at the same time, the price for leaving too soon or in an uncoordinated way could be very high."

The alliance's chief said the conflict-devastated nation "risks becoming once again a platform for international terrorists to plan and organise attacks on our homelands".

Just days ago, President Trump appointed officials in top Pentagon positions who share his frustrations over continued troop presence in the war zones.

The expected plans would cut US troop numbers almost in half by mid-January, leaving 2,500 troops in Afghanistan.