An Afghan police official says a suicide bomber, dressed in a police uniform, struck inside a police headquarters in southern Helmand province, killing one officer.

Fared Obiad, a local police spokesman, says the bombing took place on Saturday in the provincial capital of Lashkar Gah.

He says the bomber walked into a police compound but was stopped before entering a building where a security meeting was underway.

Obiad says he then detonated his explosives. The explosion killed one officer and wounded three others.

No group claimed responsibility but the Taliban have stepped up their attacks on Afghan security forces as foreign combat troops prepare to withdraw by the end of the year.

A Taliban suicide car bomber targeted a former police chief in Lashkar Gah on Wednesday, killing five people.