KABUL, Afghanistan — For the first time, the Taliban have confirmed the death of Jalaluddin Haqqani, an American ally from the Cold War who later turned his weapons against the United States as the founder of the feared Haqqani militant network, behind some of the deadliest attacks of the 17-year Afghan war.

In their announcement on Tuesday, the Taliban gave no details on the timing of Mr. Haqqani’s death. Throughout his 70s, he remained ill even as his followers continued in his name to stage huge bombings and suicide commando attacks in Afghan cities.

“Mawlawi Jalaluddin Haqqani was ill and bedridden for the past several years,” the Taliban statement said.

Afghan officials have maintained that Mr. Haqqani has been dead for at least four years — an assertion confirmed by one aide to Mr. Haqqani in 2015 — and that the Taliban have waited to use that news at some opportune moment.