The Taliban said U.S. officials recently had made new demands in the talks but did not specify what they were.
“Because of these American changes, the Taliban was obliged to stop the talks,” Mr. Mujahid said.
Mr. Panetta applauded Mr. Karzai last month for telling an interviewer that the U.S., the Afghan government and the Taliban recently held three-way talks aimed at moving toward a political settlement of the war.
The Taliban denied the claim at the time.
Afghan officials told the Associated Press that the U.S. had agreed in January to include representatives of the Karzai government in future meetings, but U.S. officials would not confirm that. U.S. officials did say that if this initial trust-building phase of contacts with the Taliban blossoms into full peace negotiations, the U.S. would sit alongside the Taliban and the Afghan government.
Associated Press writers Deb Riechmann, Heidi Vogt and Lolita C. Baldor in Kabul; Mirwais Khan in Kandahar, Afghanistan; Kathy Gannon in Islamabad; and Adam Schreck in Kuwait City, Kuwait, contributed to this report.