are thought to be benefiting from a steady influx of young, disaffected ex-Taliban recruits joining their ranks, Daily Express of Britain reported Saturday.

The rag-tag militia group has become an increasingly splintered organization in recent months amid a leadership crisis after rumors circulated that its leader Mullah Omar, who led the group for 20 years, had died.

The reclusive figure's death was only confirmed last week by the Afghan government and subsequently by the Taliban who said the one-eyed cleric had succumbed to an illness.

Fears are now being raised that fanatical Daesh militants could expand their reach into Afghanistan and Pakistan, the paper said.

Daesh's presence in the region threatens the supremacy of the Taliban, who once controlled as much as 90 per cent of the war-torn country, the paper added.

Movement of extremist fighters from the Taliban to Daesh is a "cause for concern," according to one expert in international security.

Emma Winterbotham, a specialist in violent extremism, said splits in the Taliban caused by confusion over who was in charge "could work in Daesh's favour."

She said that while there did not appear to be "coherent links" allowing militants to cross seamlessly from one group to the other, there was evidence that many jihadis – particularly youngsters – were now realigning themselves with Daesh.

"Former commanders realize that Daesh is the new thing on the block, and it is a very strategic decision in terms of generating funding," the research fellow at think tank the Royal United Services Institute claimed.

There have already been "a number of significant breakaways from the Taliban," she added, with people leaving because they didn't believe former Taliban leader Omar was still alive.

She told Express: "Omar's death does cause some room for speculation about how the Taliban will move forward and how unified it can be as a movement without the symbolic presence of the supreme leader."

The US commander in Afghanistan, Army General John Campbell, also said that the death of Omar could fracture the Taliban and demoralize its fighters, offering an opportunity for renewed peace talks.

Omar and his fellow Taliban fighters evaded capture for years despite a huge international manhunt launched in the wake of the September 11 attacks.