Sheharyar Mehsud, chief of a militant faction which is part of the umbrella Tehreek-e-Taliban Pakistan (TTP, or Pakistani Taliban), was the target of the remote-controlled blast in Kunar province, a TTP commander in Pakistan told AFP.

A Pakistani intelligence official who confirmed the incident said Mehsud had fled to Afghanistan in 2016.

The blast comes nearly two weeks after two other key TTP leaders — Khalid Haqqani and Qari Saifullah Peshawari — were killed in a clash with security forces.

It was not immediately clear who was behind the killings.

They have come as the US and the Afghan Taliban — which is separate from the TTP — appear close to a breakthrough on a deal for an American troop withdrawal from Afghanistan.

Islamabad has helped to facilitate the gruelling talks, which have stretched over more than a year.

Pakistan was one of only three countries to recognise the Afghan Taliban regime, and its shadowy military establishment — particularly the Inter-Services Intelligence (ISI) — is widely believed to back the bloody insurgency in Afghanistan.

Islamabad denies the accusation.

Pakistan has been battling a homegrown Islamist insurgency for over a decade, with thousands of civilians and security personnel dying in extremist attacks, especially after the TTP began their campaign of violence in 2007.

But overall levels of extremist-linked violence have dropped dramatically in recent years, with 2019 seeing the fewest deaths since 2007 — the year the TTP was formed.