A Taliban suicide bomber killed at least four people in Kabul in an attack on a Ministry of Defence bus, officials said, confirming three people in the vehicle and a woman bystander had died.

At least nine people were wounded in the attack in the southeast of the city early on Saturday.

"The bomber was on foot when he detonated himself next to a bus carrying Ministry of Defence staff to work," the interior ministry spokesman, Seddiq Seddiqi, told AFP.