Taliban leader Mullah Akhtar Mansour has been targeted and "likely killed" in a US drone strike in a remote area of Pakistan along the Afghan border, a US official says.

Key points: Mansour appointed head of Taliban in 2015

Mansour appointed head of Taliban in 2015 Tens of thousands of Afghan civilians were killed in attacks under his leadership

Tens of thousands of Afghan civilians were killed in attacks under his leadership Expert says death may help US effort in Afghanistan "modestly"

The airstrike, authorised by President Barack Obama, also killed a second adult male combatant as the two travelled in a vehicle south-west of the town of Ahmad Wal, but no civilians were killed, the official said under condition of anonymity.

"Mansour was the target and was likely killed," the official said.

The strikes occurred late on Friday night (local time) and were carried out by multiple unmanned aircraft operated by US Special Operations Forces, the official said.

A senior White House official said it informed Pakistan and Afghanistan "shortly after the strike" that it had conducted the attack.

Pentagon spokesman Peter Cook said in a statement that Mansour "has been the leader of the Taliban and actively involved with planning attacks against facilities in Kabul and across Afghanistan, presenting a threat to Afghan civilians and security forces, our personnel, and Coalition partners".

Mansour was appointed head of the Taliban in July 2015 following the revelation that the group's founder Mullah Omar had been dead for two years.

"Since the death of Mullah Omar and Mansour's assumption of leadership, the Taliban have conducted many attacks that have resulted in the death of tens of thousands of Afghan civilians and Afghan security forces as well as numerous US and Coalition personnel," Mr Cook said.

Mr Cook said officials were still assessing the results and would provide more information when available.

'Keep expectations in check'

Michael O'Hanlon of the Brookings Institution think tank said Mansour's death might help the US effort in Afghanistan "modestly".

"The war has been going on for so long, the Taliban has so many leaders and so much ability to function at the local level even without strong central guidance, that we would be well advised to keep expectations in check," he said.

US lawmakers welcomed the news and some called on the Obama administration to take a firmer stand.

"I appreciate President Obama for authorising the attack," Republican Senator Lindsey Graham said, adding: "I strongly encourage the Obama administration to not withdraw troops until conditions on the ground permit their withdrawal".

Republican Senator John McCain, head of the Senate Armed Forces Committee, said he hoped "this strike against the Taliban's top leader will lead the administration to reconsider its policy of prohibiting US forces from targeting the Taliban".

Part of movement from start

Born in the southern Afghan province of Kandahar sometime in the early 1960s, Mansour was part of the Taliban movement from its start in the 1990s and has effectively been in charge since 2013, according to Taliban sources.

He spent part of his life in Pakistan, like millions of Afghans who fled the Soviet occupation.

He succeeded Omar, the one-eyed warrior-cleric who led the Taliban from its rise in the chaos of the Afghan civil war of the 1990s.

"Mansur has been an obstacle to peace and reconciliation between the government of Afghanistan and the Taliban, prohibiting Taliban leaders from participating in peace talks with the Afghan government that could lead to an end to the conflict," Mr Cook said.

In addition to fighting on the ground and pressure from all sides to negotiate, the Taliban also faces the challenge of halting the expansion of the Islamic State group in Afghanistan, which has been recruiting disaffected fighters.

AFP