A suicide attacker has killed at least seven people after detonating a car bomb near a district police headquarters in the centre of the Afghan capital Kabul.

The powerful blast went off in Muradkhani district close to the presidential palace, the defence ministry and the ministry of finance on Wednesday.

"The initial reports from Kabul hospitals show seven killed and 22 wounded including women and children," Sayed Kabir Amiri, the head of hospitals in the capital, told AFP.

Interior ministry spokesman Sediq Sediqqi confirmed the attack, saying it involved a "car full of explosives that detonated near Police District 2 headquarters".

There was no immediate claim of responsibility for the attack.