A suicide bomber has killed at least nine people outside a police station in the Afghan capital Kabul, officials say.

Another 20 people were wounded in the blast in the west of the city, Deputy Interior Minister Ayoub Salangi said.

Most of the dead are reported to be civilians. The Taliban said they carried out the bombing.

The militants have mounted a string of attacks in Kabul and other parts of the country in recent months.

Monday's attack happened at the entrance of the headquarters of the National Civil Order Police, a unit that has a counterinsurgency role against the Taliban.

Officials initially blamed a suicide car bomber, but later said the attacker had joined people queuing to get into the police station before he detonated his explosives.

"I saw three dead bodies on the ground and a number of other people wounded, then ambulances arrived and took all the victims away from the attack site," one man told Reuters news agency.

The bombing follows a spate of attacks in January, one of which killed seven staff from the Tolo media group in Kabul. Several other attacks were near foreign diplomatic missions.

There has been speculation that the attacks may be aimed at destabilising attempts to revive peace talks with the Taliban.

Others have suggested that the Taliban's winter offensive may be an attempt by their new leader to strengthen his hand in any talks.