KABUL: A suicide bomber on a motorbike killed at least four people and wounded several in an attack on vehicle carrying national security officials in Kabul on Wednesday.

Media reports quoting an interior ministry official of Afghanistan confirmed the attack but could not say immediately about number of causalities.

"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," said Najib Danish, a spokesman for the interior ministry.

There was no immediate claim of responsibility for the attack.