At least 23 Afghans including 18 civilians and five police officers were killed in three separate roadside bombings on Sunday, dpa reported.
The attacks came as world leaders met in the Japanese capital Tokyo for a conference on reconstruction and development aid for Afghanistan. More than 16 billion dollars was pledged for the next four years.
Six NATO soldiers were killed in a bomb attack in eastern Afghanistan Sunday and another died in a Taliban attack in the south. The NATO death toll was the largest daily loss for international troops in four months. The military alliance did not reveal the nationalities of those killed.
Twenty Taliban fighters were also killed Sunday.
In Kandahar province, a bomb struck a civilian mini-van in Arghistan district, killing at least 10 passengers, said local police chief General Abdul Raziq.
A second bomb went off minutes later when a tractor rushed to the scene to take the injured to hospital, killing all four people onboard, he said.
In another incident in the same district, a roadside bomb hit a civilian car Sunday morning in which all four passengers including a woman and a girl were killed, a spokesman for the provincial governor said.
In neighbouring Helmand province, five police officers were killed and three injured when their vehicle drove over a roadside bomb, according to the provincial governor's spokesman.
They had been rushing to the aid of a colleagues at a police outpost in Musa Qala district, which had come under attack by Taliban militants, he said. Police had killed 20 militants in the five-hour firefight which ensued, he added.
Taliban militants rely heavily on roadside bombs, targeting Afghan and international forces.
According to a report by the United Nations, 579 civilians died in the first four months of 2012. Almost 80 per cent of the civilian causalities were attributed to Taliban insurgents.