• PESHAWAR (Pakistan) • At the Taleban meeting this week where moderate Mullah Akhtar Mohammad Mansour was named as the Islamist militant group's new head, several senior figures in the movement, including the son and brother of late leader Mullah Omar, walked out in protest.

The display of dissent within the group's secretive core is the clearest sign yet of the challenge long-time deputy Mansour faces in uniting a group already divided over whether to pursue peace talks with the Afghan government and facing a new, external threat - the Islamic State in Iraq and Syria militant group, or ISIS.

Mansour, who has been effectively in charge for years, favours talks to bring an end to more than 13 years of war. He recently sent a delegation to inaugural meetings with Afghan officials hosted by Pakistan, hailed as a breakthrough.

But Mansour, 50, has powerful rivals within the Taleban who oppose negotiations, notably battlefield commander Abdul Qayum Zakir, a former inmate of the US prison in Cuba's Guantanamo Bay.

Zakir is pushing for Omar's son Yaqoob to take over the movement, and a sizeable faction also supports Yaqoob, Reuters reported.

Yaqoob and his uncle Abdul Manan, Omar's younger brother, were among several Taleban figures who walked out of Wednesday's leadership meeting in the western Pakistani city of Quetta, according to three people who were at the shura, or gathering, Reuters reported.

"Actually, it wasn't a Taleban Leadership Council meeting. Mansour had invited only members of his group to pave the way for his election," said one of the sources, a senior Taleban member in Quetta. "And when Yaqoob and Manan noticed this, they left the meeting."

The leadership shura was held outside Quetta, where many Taleban leaders have been based since their hardline regime in Afghanistan was toppled in a 2001 United States-led military intervention.

• According to the New York Times, a range of Taleban members, including senior commanders in Afghanistan and leadership figures in Pakistan, characterise the Taleban as being in discord.

Two of the most senior militants, including a member of the group's governing body in exile, the Quetta Shura, said the leadership question would be decided at a major council meeting in the coming days.

Mansour leads the Taleban's strongest faction and appears to control most of its spokesmen, websites and statements, Mr Graeme Smith, senior Afghanistan analyst for think-tank International Crisis Group, told Reuters.

But some intelligence officials estimate Mansour only directly controls about 40 per cent of fighters in the field, he said. That could make it difficult for the new No. 1 to deliver on any ceasefire that could emerge from future negotiations.

And Taleban insiders say that by sending a three-member delegation to meet Afghan officials in the Pakistani resort of Murree earlier in July, Mansour sparked new criticism.

Especially riled were members of the Taleban's political office in Qatar, who insisted only they were empowered to negotiate, Reuters reported.

REUTERS, NEW YORK TIMES, AGENCE FRANCE-PRESSE