At least 15 people have been killed by a roadside bomb in southern Afghanistan, provincial officials say.
The explosion reportedly hit a pickup truck carrying civilians in the province of Helmand on Friday afternoon.
The office of the governor of Helmand said that the blast had taken place in the remote village of Khan Neshin.
At least six people were also hurt in a powerful explosion outside police headquarters in the city of Kandahar.
The attack in rural Helmand, on Friday, happened as a truck, carrying villagers to a nearby bazaar, ran over the bomb and detonated it, said Daoud Ahmadi, a spokesman for the provincial governor.
Four people had been injured in the blast, he said.
Mr Ahmadi blamed Taliban militants for planting the bomb, believed to be meant for American troops patrolling the area.
Helmand is one of the most violent regions of Afghanistan, with Nato troops battling Taliban rebels.
The blast in Kandahar on Saturday blew windows out of buildings up to a mile (1.5km) away, Zalmai Ayubi, spokesman for the governor of Kandahar province, said.
The BBC's Paul Wood in Kabul says British and American troops have largely achieved their aim of pushing the Taliban out of the population centres in the province, and militants now operate mainly in remote areas.
The attack in Kandahar, however, shows that the Taliban are still able to operate in that city to some extent, although the region is the focus of Nato's counter-insurgency campaign, our correspondent says.
There are also reports that five Afghan army soldiers and nine civilians were injured in a suicide attack by Taliban militants on an army checkpoint in northern Kunduz province on Saturday.
Meanwhile in eastern Paktika province, the deputy governor said seven civilians had been killed by troops of the Nato-led International Security Assistance Force (Isaf).
However, Isaf said the seven killed were insurgents who had opened fire on an Isaf patrol investigating a suspicious compound.
Our correspondent says that the row that ensued with Paktika's deputy governor is extremely damaging, given that Nato's strategy is based on developing a security partnership with the Afghan authorities.