NAYPYITAW/KABUL/ISLAMABAD: Afghan government Chief Executive Abdullah Abdullah confirmed on Sunday that Afghan Taliban leader Mullah Akhtar Mansour was killed in a United States (US) drone strike in Pakistan a day earlier.

"Taliban leader Akhtar Mansour was killed in a drone strike in Quetta, Pakistan, at 04:30 pm yesterday. His car was attacked in Dahl Bandin," Abdullah said in a tweet, referring to a district in Balochistan just over the border with Afghanistan.

Afghanistan's main intelligence service, the National Directorate for Security (NDS) also confirmed Mansour's death. "Mansour was being closely monitored for a while... until he was targeted along with other fighters aboard a vehicle," the NDS said.

Know more: Afghan Taliban chief Mansour killed in air strike: US

Pakistan seeks 'clarification' of US strike on Mansour

Pakistan is "seeking clarification" about a US drone strike against Mansour, Foreign Office Spokesman Nafees Zakaria said on Sunday, after US officials earlier said Mansour was 'likely killed' in an air strike on Pakistani soil.

"I have seen the reports. We are seeking clarification," Zakaria said in a statement.

He added that Pakistan wanted the Taliban to return to the negotiating table to end the long war in Afghanistan. "Military action is not a solution," he added.

Notified Nawaz of drone strike, says Kerry

Zakaria's statement comes as US Secretary of State John Kerry earlier on Sunday said that he notified Prime Minister Nawaz Sharif by telephone of a US drone strike that 'likely killed' Afghan Taliban leader Mullah Mansour.

Afghan leadership was also apprised of the air strike ordered by US President Barack Obama, Kerry said, declining to elaborate on the timing of the notifications.

US officials in Washington said on Saturday that US missile-firing drones had conducted strikes targeting Mansour and probably killed him in a strike in Balochistan near the Afghan border.

"Yesterday, the US conducted a precision air strike that targeted Taliban leader Mullah Mansour in a remote area of the Afghanistan-Pakistan border. Mansour posed a continuing, imminent threat", Kerry told a news conference in the Myanmar capital.

The drone attack comes just days after representatives from the US, China, Pakistan and Afghanistan held another round of negotiations in Islamabad aimed at reviving long-stalled direct peace talks between the Afghan government and the Taliban.

"This action sends a clear message to the world that we will continue to stand with our Afghan partners as they work to build a more stable, united, secure and prosperous Afghanistan," Kerry said.

"Peace is what we want. Mansour was a threat to that effort and to bringing an end to the violence and suffering people of Afghanistan have endured for so many years now. He was also directly opposed to the peace negotiation and to the reconciliation process," he said.

A senior commander with the Afghan Taliban said the militant group's leader Mullah Akhtar Mansour was killed in a US drone strike. Mullah Abdul Rauf told The Associated Press Sunday that Mansour died in the strike late Friday night. He said the strike took place "in the Afghanistan-Pakistan border area".

Afghan authorities are scrambling to confirm Mansour's fate. Afghan President Ashraf Ghani's office on Sunday confirmed the strike, adding that they were investigating whether Mansour had in fact been killed.

"The Afghan government is trying to gather details regarding the fate of Mullah Mansour," the Afghan presidential palace said in a statement. "This drone strike shows that terrorists fuelling conflict will not be safe anywhere."

"Mansour was the target and was likely killed" in the remote town of Ahmad Wal by multiple unmanned aircraft operated by US special operations forces, an American official said Saturday.

Two Pakistani intelligence officials told AFP the drones struck a Toyota Corolla near Quetta, killing two people whose bodies were burned beyond recognition.

They did not confirm whether Mansour was among them but said the bodies had been moved to a hospital in Quetta.

A member of the Quetta Shura, the Taliban's leadership council, told AFP that Mansour had been unreachable on his mobile phone since Saturday night.

"We are not sure if something is really wrong or he purposely switched off his phone fearing an attack," he told AFP on condition of anonymity.

Former ambassador to Afghanistan Rustam Shah Mohmand weighing in on the matter told DawnNews that it is "quite likely" Mansour is dead.

Pakistan's role as mediator in the peace talks will come under question, since Kerry said Nawaz was informed about the drone strike, he said.

The apparent elimination of Mansour, who swiftly consolidated power following a bitter Taliban leadership struggle after the death of Mullah Omar was revealed last year, could spark new succession battles within the fractious movement.

It is possible there may be infighting in the Taliban regarding succession after Mansour's death, particularly between Mullah Omar's brother Mullah Abdul Manan and son Mullah Yaqub, and Sirajuddin Haqqani, the Haqqani network chief, Rustam Shah Mohmand said, as Haqqani was Mansour's deputy and operational commander.

The deaths of Taliban leaders have often been falsely reported, and Mansour himself was rumoured to have been killed last December.

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

The group saw a resurgence under the firebrand supremo with striking military victories, helping to cement his authority by burnishing his credentials as a commander.

They briefly captured the strategic northern city of Kunduz in September in their most spectacular victory in 14 years. Southern opium-rich Helmand province is almost entirely under insurgent control.