File picture of Afghan Taliban leader Mullah Omar.
Taliban leader Mullah Omar died two years ago in Karachi, Afghanistan's intelligence agency spokesman Haseeb Sediqi said today.
The comments came after unnamed government and militant sources said earlier that he had died.
"Mullah Omar is dead," Sediqi, the spokesman for the National Directorate of Security, told AFP.
"He died in a Karachi hospital in April 2013 under mysterious circumstances."
Rumours of Omar's ill-health and even death have regularly surfaced in the past, but the latest claims just two days before peace talks with the insurgents mark the first such confirmation from the Afghan government.
Sediqi's statement comes after unnamed government and militant sources told media, including AFP, that the one-eyed leader died two or three years ago.
"We can confirm that Mullah Omar died two years ago in Pakistan due to an illness," a separate official in Afghanistan's national unity government told AFP earlier.
"He was buried in Zabul province (in southern Afghanistan)," said the senior official, citing Afghan intelligence sources.
The insurgents have not officially confirmed the death of the supreme leader of the Taliban, who has not been seen publicly since the 2001 US-led invasion of Afghanistan that toppled the Taliban government in Kabul.
If confirmed, Omar's death would mark a significant blow to an almost 14-year insurgency, which is riven by internal divisions and threatened by the rise of the Islamic State group in South Asia.
His death could trigger a power struggle within the movement, observers say, with insurgent sources claiming that Mullah Mansour, the current Taliban deputy, and Omar's son Mohammad Yakoub are both top contenders to replace him.