The sources, including an Afghan general and a provincial governor, said a man identified as Mullah Abdul Rauf was actively recruiting fighters for the group, which controls large parts of Syria and Iraq, AP reports.

Gen. Mahmood Khan, the deputy commander of the army's 215 Corps, said that within the past week residents of a number of districts in the southern Helmand province have said Rauf's representatives are fanning out to recruit people.

"A number of tribal leaders, jihadi commanders and some ulema (religious council members) and other people have contacted me to tell me that Mullah Rauf had contacted them and invited them to join him," Khan said.

But he said the Taliban, which is active across Helmand and controls some districts, have warned people not to contact Rauf.

"People are saying that he has raised black flags and even has tried to bring down white Taliban flags in some areas," said Saifullah Sanginwal, a tribal leader in Sangin district. "There are reports that 19 or 20 people have been killed" in fighting between the Taliban and the IS group, he added.

Rauf was a corps commander during the Taliban's 1996-2001 rule of Afghanistan, according to Amir Mohammad Akundzada, the governor of Nimroz province neighboring Helmand. Akundzada said he is related to Rauf but has not seen him for almost 20 years.

Both Khan and Akundzada said Rauf was apprehended after the fall of the Taliban in the U.S.-led invasion of Afghanistan and was detained for years at Guantanamo Bay.

Khan and Akundzada suggested Rauf may have fallen out with the leaders of the Afghan Taliban after spending time in the Pakistani city of Quetta, where Afghan officials and analysts believe senior Taliban leaders are based.

Tehreek-e-Taliban Pakistan (TTP) spokesman Shahidullah Shahid (sitting) speaks during a press conference at an undisclosed location in Pakistan on February 21, 2014.

A video released online Saturday purports to show militants from both Afghanistan and Pakistan pledging support to IS.A militant identified by the SITE intelligence group as former Pakistani Taliban spokesman Shahidullah Shahid is then seen addressing the crowd to announce pledges of allegiance to ISIS from leaders of various groups in Afghanistan and Pakistan.

But Akundzada said ISIS was not likely to gain traction with ordinary Afghans. "People who want to fight in Afghanistan just create new names — one day they are wearing white clothes (of the Taliban) and the next day they have black clothes and call themselves Daesh, but they are the same people," he said.

In Washington, State Department spokeswoman Marie Harf said the U.S. has noted the "rhetorical message of support for the Islamic State group by some in Afghanistan.”
"We continue to watch for signs that these statements could amount to something more than just rhetorical support," she said. "That doesn't mean it's unimportant."

Analysts say most claims of allegiance to IS in Afghanistan have been motivated by opportunism and that a new "jihadist outfit" would find it difficult to establish a presence where there are already long-established militant groups with tribal links. The Taliban have confined their insurgency to Afghanistan, and do not espouse the pan-Islamic model of jihad embraced by the Islamic State.

Parts of Helmand have seen fierce fighting between the Taliban and Afghan security forces since U.S. troops pulled out more than six months ago.