The Taliban also announced his deputies -- Sirajuddin Haqqani, who leads the Taliban-allied Haqqani network and has a $10 million US bounty on his head, and Haibatullah Akhundzada, former head of the Taliban courts.

The announcment of Mansour -- seen as a moderate and a proponent of peace talks -- comes a day after the Taliban confirmed the death of their near-mythical leader Mullah Omar, who led the fractious group for some 20 years.

The power transition raises hopes that Mansour's leadership will pave the way for an end to nearly 14 years of fighting as the US-backed Afghan government struggles to contain the Taliban's intensifying summer offensive.

Mansour, a longtime trusted deputy of Omar, takes charge as the Taliban confronts growing internal divisions and is threatened by the rise of the so-called “Islamic State” group, the Middle East terrorists outfit that is making steady inroads in Afghanistan.

"After (Omar's) death the leadership council and Islamic scholars of the country, after long consultations, appointed his close and trusted friend and his former deputy Mullah Akhtar Mansour as the leader," the Taliban said in a Pashto-language statement posted on their website.

"When Mullah Omar was alive, Mullah Mansour was considered a trustworthy and appropriate person to take this heavy responsibility."

A Taliban official said the process to choose Omar's successor had several stages: the group's ruling council would choose a candidate who must then be approved by a college of religious clerics.

The top contenders included Mansour and Omar's son Mullah Yakoub, who sources said was favoured by some commanders but at 26 was considered too young and inexperienced for such a key role.