A roadside bomb hit a tractor in southern Afghanistan on Monday, killing seven civilians and wounding four others, officials said.
The tractor and trailer hit the anti-vehicle mine in the Mali Zai area of Zabul province, the ministry of interior said in a statement.
"Seven civilians were killed and four other civilians were wounded. The wounded were taken to the hospital by Afghan National Police," the statement said.
The details of the blast were not immediately available and no-one has claimed responsibility, but roadside bombs and mines are the weapon of choice for the Taliban, who have led an 11-year insurgency against the government of President Hamid Karzai and its Western allies.
A roadside bomb exploded under an Afghan bus in neighbouring Ghazni province on April 8, killing nine civilians and wounding at least 22 others in an attack blamed on Taliban militants.
A day before that, a suicide car bomber struck a NATO convoy in Zabul, killing three US soldiers and two civilians, including a female American diplomat travelling with Afghan officials to distribute books to students.