Three Afghan civilians were killed along with 14 insurgents in a NATO air strike targeting a Taliban commander and seven more people also died in separate blasts, Afghan authorities said on Monday.
The air strike in southern Helmand province came only a day after another air strike by foreign forces targeting insurgents in different district of the province, which Afghan police said also killed civilians as well as fighters.
Deaths of civilians in NATO attacks have fuelled tensions between President Hamid Karzai and his Western allies, who are under increasing pressure at home over the unpopular war.
Monday's strike on a compound in the province's Kajaki district killed 14 insurgents and three civilians, said provincial police intelligence chief Kamaluddin.
A spokesman for the NATO-led International Security Assistance Force (ISAF) said it was investigating the report of a strike, but did not have any information.
Four bodies and 10 wounded civilians were also brought to hospitals in southern Kandahar city on Monday after a series of blasts, doctors there said.
Three explosions occurred just minutes apart in the nation's largest city in the south, the Associated Press reported. At least two policemen were killed, said Zelmai Ayubi, a spokesman for the provincial governor of Kandahar.
Officials at Mirwais Hospital reported a higher death toll. They say four policemen died in the explosions and 17 other people were injured.
The vicitms had been caught by three explosions near a convoy of troops travelling out of Kandahar City, border police official Abdul Razzaq told Reuters. Gunshots were also heard soon after the blasts, he added.
Investigators are still trying to determine what type of explosives were detonated.
An ISAF spokesman said he had heard reports of an incident in Kandahar but the coalition's vehicles had not been targeted.
In a separate attack, a rocket hit a residential area in the the Andar district of Ghazni in southern Afghanistan, provincial police said. Officials did not say who fired the rocket.
At least three Afghan civilians were killed along with 17 insurgents in a NATO air strike in Helmand's Nad Ali district on Sunday, police said. ISAF said it was aware of the reports of civilian casualties but declined immediate comment.
The war is now in its bloodiest year since the 2001 U.S.-led invasion that ousted the Taliban from power. Civilians are killed by both sides, but NATO says it has taken strong steps since last year to reduce the number of civilians it kills.