Media reports say at least 17 people have been killed in a suicide car bombing near a military base where Afghan and foreign soldiers are stationed in the eastern province of Khost.
The AFP news agency cited Khost city police chief Faizullah Ghairat as saying the bomber detonated explosives at a military roadblock near the entrance to the base on July 12.
"We counted 18 dead," AFP quoted a doctor at a hospital in the city as saying.
The Associated Press cited a doctor as saying at least 17 people were killed and referred to the facility as a U.S. base.
The attack came after authorities said at least 12 Afghan civilians were killed in two separate roadside bomb explosions in the country's east and north.
Abdul Karim Fayeq, provincial police chief in Kapisa Province, said on July 12 that 10 civilians were killed and at least seven others wounded after their vehicle was hit by a roadside bomb.
Fayeq said the incident took place in Tagab district, where militants are active and regularly attack Afghan security forces.
Three civilians were also killed and 10 wounded by a roadside bomb in the northern province of Kunduz.
The provincial police spokesman said the explosion occurred near an Afghan police recruiting center in Kunduz city, the provincial capital.
The incident occurred after a police vehicle struck a roadside mine.
No group claimed immediate responsibility for the two bombing, but the Taliban has been blamed for similar attacks in the past.