(Reuters) - A suicide attacker wearing a police uniform attacked a provincial police headquarters in southern Afghanistan on Saturday, killing one officer and wounding four other people, an official said.

The bombing in Helmand province is the latest by militants bent on weakening the Afghan security forces ahead of the withdrawal of most foreign troops at the end of this year.

The unidentified attacker approached the police compound in Lashkar Gah, the provincial capital, wearing a police uniform but was stopped by a guard at the entrance, said Farid Ahmad Obaidi, a spokesman for the Helmand provincial police chief.

The bomber detonated his suicide vest, killing one nearby police officer and wounding three other police and an army soldier, he said.

Taliban insurgents and their jihadist allies have been stepping up attacks in Helmand. In 2009, a U.S. troop surge focused on wresting back control of the strategic province. 

Most U.S. troops withdrew from Helmand earlier this year, and Afghan security forces have been fighting insurgents there.

Since the Taliban was ousted from power by the U.S.-led intervention after the Sept. 11, 2001 terrorist attacks in the U.S., it has been seeking to re-establish its former hard-line Islamic state.

Close to half of Afghanistan's opium, a major funding source for the insurgency, is produced in Helmand, according to the United Nations

(Reporting by Mohammad Stanekzai. Writing by Kay Johnson; Editing by Richard Borsuk)