Roadside bombs killed 18 civilians travelling in three vehicles in Afghanistan's southern Kandahar province close to the Pakistan border on Sunday, police said.
"The first blast hit a minivan with around 20 people on board," provincial police chief General Abdul Raziq told AFP.
"A tractor came to pick up the bodies and injured people but a second explosion hit it too and altogether 14 people, including five women, were killed and nine wounded," he said.
A third civilian vehicle was hit by another roadside bomb in the same district hours later, killing four, including two women, he said.
He blamed the attacks on Taliban insurgents, hardline Islamists who have been waging a decade-long campaign to topple the government of President Hamid Karzai, which is backed by 130 000 Nato troops.
The deaths come a day after bomb blasts and a rocket attack in southern Afghanistan killed 11 civilians, including at least four children, in the space of 24 hours.
For the past five years the number of civilians killed in the war has risen steadily, reaching a record 3021 in 2011 — the vast majority caused by insurgents, according to UN figures.