KABUL (Reuters) - A Taliban suicide bomber attacked a convoy of the Afghan national intelligence agency in Kabul early on Thursday, causing an unknown number of casualties, officials said.

The attack, which was claimed by the Taliban, occurred at around 5 a.m. (0030 GMT) when a car bomber targeted the convoy in the west of the city, Kabul police spokesman Hashmat Stanekzai said.

It was not immediately clear how many casualties had been caused or whether they were civilians or members of the security services. Stanekzai said four people had been killed and five wounded, while a spokesman for the ministry of public health said three wounded had been brought into city hospitals.

A Taliban statement said the attack had caused tens of casualties among the security services.