"If Yemen is the world’s worst humanitarian disaster, Afghanistan suffers its deadliest fighting. In 2018, by one tally, the war killed more than 40,000 combatants and civilians," reported Crisis Group.

"In 2018, the war exacted a higher toll than at any time since the Taliban were ousted from Kabul more than seventeen years ago," it said.

Meanwhile, the US government is planning to reduce its troops posted in Afghanistan, media reports said on Friday.

The US military has been ordered to begin planning to withdraw about half the troops in Afghanistan, a US defence official with direct knowledge of the matter told CNN on Thursday.

The official told the US news channel that the planning is underway, and it could take months to withdraw the nearly 7,000 troops.

The decision has been taken at a time when the US also announced its move of withdrawing its military from Syria.

Several US defence officials told CNN that Trump wants to draw down US troops in Afghanistan.