Suicide bomber targets Nato base in Afghanistan Afghan police carry the body of a civilian into a hospital morgue after the suicide attack in Khost province. Photograph: Mohammad Rasool Adil/AFP/Getty Images A suicide bomber driving a minibus full of explosives has attacked a base in eastern Afghanistan used by Nato troops and CIA operatives, killing three Afghan civilians and a security guard and injuring at least seven others. The attacker struck when his vehicle was detained at a checkpoint a short distance from the east gate of the base in Khost province, also known to locals as "the old airport," the deputy provincial governor Abdul Waheed Patan told the Guardian. "The security people stopped the bus at the checkpoint, but he kept going for a few more metres then detonated the explosives," Patan said by phone from Khost. Two drivers who bring passengers from town to the area near the base, one civilian passerby and one security guard were killed. The provincial police chief, General Abdul Qayoum Bakaizoi, confirmed the attack had happened at around 8am near one of two main gates to Forward Operating Base (FOB) Chapman. The attack came almost exactly three years after a much more devastating suicide bomber hit US intelligence officers operating out of FOB Chapman. A Jordanian doctor and militant posing as a double agent, he killed the station chief and six other CIA employees as well as a Jordanian intelligence official. The assault on 30 December 2009 was the deadliest on the CIA in more than two decades, and the second worst in the agency's history. In contrast, the Boxing Day attacker did not make it inside FOB Chapman, and no foreign soldiers were killed in the attack, a spokesman for the Nato-led coalition said. The Taliban claimed responsibility for the bombing by text message and email, saying they had targeted dozens of Afghans working for foreign forces. Patan blamed militants who had crossed over from nearby Pakistan. We have 184km [114 miles] of border with Pakistan. The main problem is that we have no border control so people can just come across. Khost is one of the most dangerous provinces in Afghanistan, a stronghold of the Haqqani network, perhaps the most ruthless and tightly organised of the militant groups that nominally defer to Taliban leadership of the insurgency. The attack comes just two days after a policewoman shot dead a US adviser in police headquarters in Kabul, the latest in a string of insider shootings by Afghan police and soldiers of the foreigners meant to be mentoring or fighting alongside them. The interior ministry spokesman said the shooter was an Iranian national, who had married an Afghan and years ago got fake papers that allowed her to live and work in Afghanistan. She had displayed "unstable behaviour" and investigators had discovered no links to the Taliban. The insurgents, who very rarely use female combatants, denied any role in the killing.