PESHAWAR - The Afghan Taliban's new leader is wooing powerful figures from the militant movement based in the Middle East who have not yet publicly pledged their support, sources within the group say, as he attempts to stifle a brewing challenge to his position.

A battle for the top job could worsen violence in Afghanistan by triggering Taliban-on-Taliban fighting and in turn doom fledgling peace talks between the Afghan government and the insurgency.

It could also make it easier for Islamic State to expand its influence in one of the world's most unstable regions.

Mullah Mansour was hastily appointed leader of the Taliban, the Islamist insurgency fighting to overthrow the Afghan government, in July after the Afghan spy agency leaked the death of Mullah Omar, founder of the movement.

Mansour was Omar's deputy. Many commanders were outraged that Mansour concealed news of Omar's death for more than two years and boycotted the meeting that appointed him.

Mansour said the deception ensured Taliban unity amid the 2014 withdrawal of NATO troops.

Despite his efforts, as rumours of Omar's death grew stronger, at least three Afghan insurgent factions pledged allegiance to Islamic State, a Middle Eastern group known for public executions and systematic rape in Iraq and Syria.

In recent weeks, Mansour sent Mullah Jalil, an envoy with good contacts with the Taliban's political leadership, to persuade senior members based in the Middle East to publicly support him instead of a rival faction coalescing around Omar's brother and son, Taliban insiders said.

The Taliban operate a political office in Qatar and also frequently hold informal meetings with diplomats in the United Arab Emirates. (Reuters)