Three suicide bombers launched a coordinated assault on a police headquarters in southern Afghanistan overnight, damaging the compound and sparking a gun battle, officials said Monday. The attack underscored the growing threat posed by the Taliban in Kandahar, their spiritual home and the focus of a US-led push to beat back a nine-year insurgency in a bid to allow American forces to start withdrawing next year. The first suicide attacker detonated a motorcycle rigged into a bomb outside the border police compound in the city, destroying the outer wall of the compound, said senior police official Mohammad Ashraf Gharzai. Two other suicide attackers then ran into the compound after the blast and opened fire on border policemen in the building, said Gharzai. "After a 40-minute gun battle both suicide attackers were shot and the explosives strapped to their bodies went off," Gharzai told AFP, adding that he had been at the compound when the attacks took place. "Only four policemen were slightly wounded," he added. The compound had most of its windows broken and was littered with bullets, blood and the suicide attackers' body parts, an AFP reporter said. Yousuf Ahmadi, a Taliban spokesman, claimed responsibility for the attack but said the motorcycle bomb had been detonated by remote-control. The Afghan interior ministry confirmed the attack and that three policemen were wounded. In eastern Afghanistan, another Taliban stronghold, militants ambushed and killed a pro-government cleric along with his brother and his driver in Kunar province, officials said. Rehman Gul was a former anti-Soviet resistance commander and prominent tribal elder in the district of Chapa Dara. He played a mediator's role in tribal disputes in the district and was respected by the community, provincial police chief Khalilullah Ziyayee said. Speaking to AFP, Ziyayee blamed Sunday's attack on "enemies of Afghanistan," a term often used to refer to Taliban insurgents. Violence has increased in southern Afghanistan, where the United States is focusing a military build-up that will bring the overall number of foreign troops in the country to a record 150,000 by August.