The move came after Taliban fighters secured complete control over all districts in Badghis province, reflecting wider gains by the group over territory and infrastructure since a US troop withdrawal announcement.
An Afghan official said "an indefinite ceasefire" had been negotiated with local Taliban leaders in a western province that had come under assault by the militants in their sweeping campaign across the countryside.
Badghis governor Hesamuddin Shams said on Thursday no time frame had been set for a truce, which comes after the Taliban last week stormed the provincial capital Qala-e-Naw – their first major attack on a city since US-led foreign forces began their final withdrawal from the country in early May.
"The ceasefire between Afghan security forces and the Taliban began at around 10:00 am today (0630 GMT). The ceasefire was brokered by tribal elders," Shams told AFP.
"Ten tribal elders had taken the responsibility of ceasefire, so they first talked to the Taliban, and then talked to the local government and both sides reached a ceasefire," Shams said.
A spokesman for the Taliban denied they had agreed to a ceasefire but said they had left the city to avoid civilian casualties. "Qala-e-Naw is the only city in Afghanistan where the Taliban announced a ceasefire," said Abdul Aziz Bek, the head of the provincial council in Badghis. Afghan officials in the capital, Kabul, were not available to comment.
Taliban's speedy advance
After taking hold of the rest of the province, Taliban militants swooped on Qala-e-Naw, where Afghan forces and Taliban fighters engaged in street battles.
Afghan forces, which have been facing a crisis in the country, later said they had flushed the militants out of the city.
The Taliban have captured scores of districts across the rugged countryside, as well as key border crossings with neighbouring countries, choking off revenues much needed by Kabul while also filling their own coffers.
On Wednesday, they captured the border crossing of Spin Boldak along the frontier with Pakistan, raising their flag above the town.
Strategic border crossing closed
Pakistan's foreign ministry confirmed on Thursday that the Afghan side of the border crossing was in the militants' hands.
Border officials on the Pakistan side in Chaman swiftly shut the crossing, causing chaos for traders and families queuing up to cross.
"An unruly mob of about 400 people tried to cross the gate forcefully. They threw stones, which forced us to use tear gas," said a security official on the Pakistan side, who asked not to be named, adding that the situation was later brought "under control".
He said around 1,500 people had gathered at the border Wednesday waiting to cross.
An Afghan Taliban source told AFP that hundreds of people had also gathered on the Afghan side, hoping to travel in the other direction.
"We are talking to Pakistani authorities. A formal meeting to open the border is scheduled for today, and hopefully, it will open in a day or two," he said.
Later on Thursday, a Pakistani border official told AFP that the border would open Friday for pedestrians from both sides.
The crossing provides direct access to Pakistan's Balochistan province, where the Taliban's top leadership has been based for decades, along with an unknown number of reserve fighters who regularly enter Afghanistan to help bolster their ranks.
A major highway leading from the border connects to Pakistan's commercial capital Karachi and its sprawling port on the Arabian Sea, which is considered a linchpin for Afghanistan's billion-dollar heroin trade that has provided a crucial source of revenue for the Taliban's war chest over the years.
Soon after capturing Spin Boldak border town, scores of Taliban fighters rampaged through the town, looting homes and seizing vehicles of government officials who had fled, according to local residents.
"The bazaar is closed and traders are scared that the situation will turn bad," Mohammad Rasoul, a trader in Spin Boldak, told AFP by phone.
"They fear that their products will be looted. There are scores of opportunists waiting to loot."
Taliban offer three-month ceasefire in return for prisoner release
Islamabad on Thursday announced it had invited a number of "Afghan leaders" to a peace conference over the weekend, but an aide to Afghan President Ashraf Ghani told local media his government had asked for it to be postponed, with politicians already heading to Qatar.
Nader Nadery, the spokesman for the government's negotiating team in Doha where peace talks with the Taliban have been stalled for months, said the Taliban have offered a three-month ceasefire in return for thousands of prisoners being released.
"The Taliban has offered a plan for a three-month ceasefire, but in exchange they have asked for the release of 7,000 of their prisoners and the removal of their leaders from the UN blacklist," he told reporters in Kabul.
A spokesman for the Taliban said he was only aware of the suggestion of a ceasefire over the forthcoming Eid al-Adha holiday.
However, he later said that no formal proposal had been made.
Peace talks launched in Qatar last year have so far failed to reach any political settlement, and the latest offensives suggest the insurgents are now set on a military victory.