The Taliban closed a key border crossing with Pakistan on Friday, saying no one would be allowed through until Islamabad dropped or relaxed its visa requirements for Afghans.

The Taliban, wresting control of Afghanistan in the wake of a withdrawal of US and other foreign troops, last month captured the southeast Chaman-Spin Boldak border crossing from Afghan forces.

Pakistan initially closed its side of the crossing, landlocked Afghanistan's second busiest entry point and main commercial artery to the sea, before reopening it last week.

In a statement on Friday, the Taliban statement called on Pakistan to scrap all visa requirements for Afghans.

"(The crossing) will remain closed for all types of commuting, including transit and trade, for both sides, and pedestrians, until the Pakistani side leaves the gate open, morning to evening, for Afghans holding [Pakistani issued] migration cards or [Afghan] ID cards," the insurgent group's shadow governor for Kandahar province said in the statement.

Taliban spokesman Zabihullah Mujahid said the group's leadership had endorsed the move, and on Friday the border had been closed.

Since US-led foreign troops began leaving Afghanistan earlier this year, fighting between the Taliban and Afghan forces has escalated significantly. In recent weeks, the Taliban have advanced rapidly on provincial capitals and targeted top government officials inside Kabul.

The Taliban have also taken control of several border crossings, including with Iran and Central Asian countries, but the crossing with Pakistan provides a significant customs revenue.

Ensuring it is open for visa-free travel would not only curry favour with ordinary Afghans, but also shore up a route to parts of Pakistan that have historically housed the insurgent group's fighters and part of its leadership.

Afghan government data indicates the route was used by 900 trucks a day before the Taliban seized it.

Read more: Double tax and bandits on the Pakistan-Afghan trade route

The closure could impact import of medicines and other essential goods as violence has sharply escalated in Afghanistan amidst a pandemic, with the United Nations saying hundreds of thousands have been displaced internally.

Spokespersons for Pakistan's Foreign and Interior ministries did not respond to requests for comment from Reuters.

Pakistani border officials at Chaman told Reuters the Taliban had placed concrete barriers to block the road on their side of the Friendship Gate, the crossing point between the two countries.

Many Afghans living in Pakistan have been issued migration cards by Islamabad allowing them to stay, but those who want to enter Pakistan today need to obtain a visa.