Afghan Taliban leader Mullah Akhtar Mansour has probably been killed in a US air strike, US officials say.
He and another male combatant were targeted as they rode in a vehicle in a remote area of Pakistan close to the Afghan border, the officials said.
The Pentagon has confirmed it targeted Mansour in strikes but said they were still assessing the results.
Mansour assumed the leadership in July 2015, replacing Taliban founder and spiritual head Mullah Mohammad Omar.
The operation took place near the town of Ahmad Wal at around 15:00 (10:00 GMT) on Saturday and was authorised by President Barack Obama.
Both Pakistan and Afghanistan were informed about the strike, said a US State Department spokesperson, without clarifying whether the notification was made in advance.
"We are still assessing the results of the strike and will provide more information as it becomes available," said Pentagon spokesperson Peter Cook.
An unnamed Taliban commander told the Reuters news agency: "We heard about these baseless reports but this not first time. Just wanted to share with you my own information that Mullah Mansour has not been killed."
False rumours have often surrounded Taliban leaders.
Omar died in 2013 but this was only confirmed by the Taliban two years later, while Mansour was reported to have been killed in a gun battle last year, something dismissed by the Afghan government.
Mansour's appointment as Taliban chief was disputed, with a rival group selecting their own leader.
The Pentagon's statement said Mansour was actively involved with planning attacks "presenting a threat to Afghan civilians and security forces, our personnel, and Coalition partners".
The Taliban have made gains since international troops withdrew from an active fighting role in 2014.
Nato forces are increasingly being deployed in battle zones to support Afghan forces fighting the Taliban.
Who is Mullah Mansour?
- Long seen as acting head of the Taliban, and close to its founder Mullah Omar
- Born in the 1960s, in Kandahar province, where he later served as shadow governor after the Taliban's fall
- Was civil aviation minister during the Taliban's rule in Afghanistan
- Had an active role in drug trafficking, according to the UN
- Has clashed with Abdul Qayum Zakir, a senior military commander, amid a power struggle and differences over negotiations with the Afghan government
- A man claiming to be Mansour met former Afghan President Hamid Karzai for peace talks in 2010 - but it later emerged he was an imposter