A suicide bomber blew himself up alongside a minivan carrying foreigners on a busy highway leading to the airport in the Afghan capital on Tuesday, police said, killing six people.

"There has been a suicide bombing next to a minivan, carrying foreigners. There are a lot of casualties. I cannot give you a number at this time, but there are alot of casualties," Kabul police chief Mohammad Ayoub Salangi told AFP.

An AFP photographer at the scene said he saw six bodies.