An explosion outside the office of the governor of the southern province of Helmand killed 12 people today.
The bomb went off as foreign troops were passing in the provincial capital, Lashkar Gah, an official said.
"It was a suicide attack on a road in front of the governor's office," said a police spokesman. He initially said 12 people had been killed, although a provincial spokesman later said the toll was 18.
There was no immediate claim of responsibility, but Taliban insurgents have intensified their war against the government and foreign troops supporting it this year. Violence is the most intense since the Taliban were ousted in 2001.