Their visit to Karachi came a day after Afghan President Ashraf Ghani threatened diplomatic reprisals against Pakistan if it refused to take action against Taliban leaders, a new hardline stance after a brazen insurgent attack killed 64 people in Kabul.

A senior Afghan Taliban source based in Pakistan told AFP the three-member team would "soon begin initial contacts with Pakistani and Afghan officials".

"The main purpose of the visit is to explore ways and means to bring peace in Afghanistan," the source, who is based in northwest Pakistan, told AFP.

"It is an initial stage and formal peace talks have yet to begin. They have arrived on Pakistan's invitation," he added.

Two other Afghan Taliban sources confirmed the arrival of the negotiating team, though Pakistani and Afghan officials have yet to formally comment.

Qari Yousuf, one of the Taliban's official spokesmen, said he was unaware of the visit.

Direct peace talks between Kabul and the Afghan Taliban began in Pakistan in July 2015 but were scrapped after the belated revelation that Mullah Omar, the group's founder, had died two years earlier.

The disclosure sparked infighting within the militant group.

A four-member group comprising Afghanistan, the US, China and Pakistan has been attempting since January to revive the talks. But the lack of progress has left many frustrated, as the Taliban ramp up their insurgency which began in 2001 after they were deposed from power by a US-led invasion.

Ghani angrily denounced Pakistan for failing to rein in the Taliban.

Islamabad recently admitted, after years of official denial, that the Taliban leadership enjoys safe haven inside Pakistan.

"I want to make it clear that we no longer expect Pakistan to bring the Taliban to the negotiating table," Ghani said in a sombre address to both houses of the Afghan parliament.

"But we want Pakistan to fulfil its promises... and take military action against their sanctuaries and leadership based on its soil. If they can't target them they should hand them over to our judiciary."

The Taliban have repeatedly said they will not negotiate until their demands are met, including the departure of 13,000 foreign soldiers deployed to train and advise their Afghan counterparts.

The April 19 bombing in Kabul, which also wounded nearly 350 people, was seen as the opening salvo in this year's Taliban offensive - widely expected to be the bloodiest in 15 years.