Ataullah Khogyani, spokesman for the provincial governor in Nangarhar, said the number of Islamic State group dead was up from the 36 reported a day earlier. A Ministry of Defense official had said Friday the number of dead could rise as officials assessed the bomb site in Achin district.
"Fortunately there is no report of civilians being killed in the attack," Khogyani said.
The increased death toll in Nangarhar was announced as officials in southern Helmand province reported at least 11 civilians were killed and one wounded in two roadside bomb blasts overnight.
The U.S. attack on a tunnel complex in remote eastern Nangarhar province near the Pakistan border killed at least four IS group leaders, Khogyani said. He said a clearance operation to assess the site of the attack was continuing.