However, the BBC added that Taliban have not commented upon the death of Mullah Omar.
A Taliban spokesman said the group would certainly issue a statement shortly, the BBC said in a report on its website.
Mullah Omar, the one-eyed warrior-cleric, was the supreme commander and the spiritual leader of the Taliban.
In the past 13 years, Omar had stayed completely out of the public eye amid growing power struggles within the Taliban and fears of the IS group’s influence in their ranks as an ideological rival.
In April, the Afghan Taliban published a descriptive biography of their “charismatic” supreme leader Mullah Omar, in a surprise move apparently aimed at countering the creeping influence of the Islamic State group within insurgent ranks.
The Taliban have reportedly seen defections to the Islamic State in recent months, with some insurgents expressing their disaffection with Mullah Omar who had not been seen since the 2001 US-led invasion of Afghanistan.