The United States and the Taliban are set to sign a historic agreement that would pave the way to ending America's longest war, the two sides have announced.

The development comes hours after Kabul said a week-long partial truce across Afghanistan would begin this weekend.

If the so-called "reduction in violence" holds, it would mark a major turning point in the conflict and set the conditions for a deal that could, ultimately, result in US troops leaving Afghanistan after more than 18 years and leave the country facing an uncertain future.

Both US Secretary of State Mike Pompeo and the Taliban issued statements saying they had agreed to sign the accord on 29 February in Doha, following the one-week partial truce.

"Upon a successful implementation of this understanding, signing of the US-Taliban agreement is expected to move forward," Mr Pompeo said, adding negotiations between the Taliban and the Afghan government would "start soon thereafter".

Afghanistan's National Security Council spokesman Javed Faisal and Taliban sources earlier said the "reduction in violence" between US, Taliban and Afghan security forces would begin tomorrow.

The US has been in talks with the Taliban for more than a year to secure a deal in which it would pull out thousands of troops in return for Taliban security guarantees and a promise to hold peace talks with the government in Kabul.

A reduction in violence would show the Taliban can control their forces and demonstrate good faith ahead of any signing, which would see the Pentagon withdraw about half of the 12,000-13,000 troops currently in Afghanistan.

In a statement, the Taliban said warring parties would "create a suitable security situation" ahead of a deal signing.

One Taliban source in Pakistan said that if an agreement is signed on 29 February, talks between the Taliban and the Afghan government, needed to cement a broader peace deal, are slated to start 10 March.

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In Afghanistan's southern province of Kandahar, which is seen as the Taliban's heartland, one insurgent said he had received orders to stand down.

However another Taliban commander based in Kandahar said he had only been ordered to refrain from attacking major cities and highways.

Taliban expert Rahimullah Yusufzai said the move signalled a wider change in thinking for both the Taliban and the US after years of fighting.

"Both sides have shown their commitment to sign the peace deal, and it's a big development - a significant one," he said.

The US and the Taliban have been close to a deal before, only to see President Donald Trump veto it at the 11th hour in September amid continued insurgent violence.

Any truce comes fraught with danger, and analysts warn the attempt to stem Afghanistan's bloodshed is laced with complications and could fail at any time.

Worse still, they say warring parties could exploit a lull to reconfigure their forces and secure a battlefield advantage.

The reduction in violence is "still just the first step to get to intra-Afghan negotiations," Andrew Watkins, a senior analyst with the International Crisis Group, said.

"Those talks will be a tough road of their own, but are the best avenue to peaceful settlement to Afghanistan's conflict."

Yesterday, the deputy leader of the Taliban said the insurgents are "fully committed" to a deal with Washington.

"That we stuck with such turbulent talks with the enemy we have fought bitterly for two decades, even as death rained from the sky, testifies to our commitment to ending the hostilities and bringing peace to our country," Sirajuddin Haqqani wrote in an opinion piece in the New York Times.

Mr Haqqani is also head of the Haqqani network, a US-designated terrorist group that is one of the most dangerous factions fighting Afghan and US-led NATO forces in Afghanistan.

Since the US-led invasion of Afghanistan after the 11 September 2001 attacks, America has spent more than $1 trillion in fighting and rebuilding in Afghanistan.

About 2,400 US soldiers have been killed, along with tens of thousands of Afghan troops, Taliban fighters and Afghan civilians.