In an interview with The New York Times, hours after he said he intended to work toward “ousting the U.S.,” a fuming Mr. Karzai said there was no justification for the United States to drop its most powerful conventional bomb in Afghanistan. The weapon, the GBU-43/B Massive Ordnance Air Blast, is referred to as the “mother of all bombs.”

He accused the American military of using the presence of Islamic State militants to turn his country into a laboratory for testing its weapons.

Mr. Karzai said President Ashraf Ghani’s government had been an “accomplice” that allowed and welcomed the use of the bomb. Mr. Ghani’s government had said the attack — which was said to have killed dozens of militants and destroyed three large caves in Nangarhar Province — was coordinated with the United States.

“Shame on him for saying that, shame, shame,” he said. “No Afghan with self-respect would do that.” Mr. Karzai added, “He is a traitor, a traitor.”