At least four people have been killed and several others injured after a suicide attack in Kabul, Afghanistan.

A security official said a suicide bomber was riding a motorbike and targeted a vehicle carrying national security officials.

There was no immediate claim of responsibility for the attack.

An interior ministry official confirmed the attack but could not say how many people had been killed or injured.

"The suicide bomber was on a motorbike and detonated himself in the Pul Mahmood Khan area (in Kabul). The target is unclear but there were casualties," interior ministry spokesman Najib Danish said.