A suicide car bomb exploded outside a US military base in Afghanistan on Wednesday, killing seven Afghans in the second deadly attack to strike the town of Khost in two days, officials said.
File photo shows a US soldier walking through Base Salerno on the ouskirts of Khost in Afghanistan. (AFP Photo)
The insurgent Taliban movement claimed responsibility for the blast, saying the bomber was one of 30 it let loose in the eastern town, some of whom carried out a series of attacks Tuesday that killed up to nine Afghans.
Eleven of the attackers were killed on Tuesday, the defence ministry said.
Wednesday's bomb exploded at a gate where labourers were waiting to enter a large US military base called Salerno, on the outskirts of the town, to start work, said an AFP reporter.
Most of the casualties were these men, officials at the base told reporters.
"Twenty-one local nationals were wounded and seven were killed," Specialist April Campbell told AFP from the main US base in Afghanistan at Bagram, north of the capital Kabul.
The Khost province police chief Abdul Qayoum Baqizoi said: "It was a car bomb but we have no information about the casualties at this point."
A man who said he was a local member of the Taliban named Salahuddin warned there would be more strikes on the city. The bomber at the base was one of 30 who had been sent into the town, he said.
Eleven suicide bombers were killed in Khost on Tuesday in a nearly day-long standoff that Afghan officials said left between six and nine Afghans dead and around 30 wounded.
A series of attacks rattled the small town about 20 kilometres (12 miles) from the border with Pakistan, which has come under regular attack as the Taliban-led insurgency has escalated.
Militants, whom officials and witnesses said were dressed in burkas and uniforms, targeted the offices of the governor and the municipality.
The interior ministry said there were 10 attackers, one of whom tried to ram the governor's offices with a car bomb that exploded outside, killing four security guards on the spot.
Nine others targeted the nearby municipality, four of them blowing themselves up outside the building as the remainder stormed inside apparently intent on taking hostages, it said.
It took nearly six hours for combined forces to stop the militants, the Afghan defence ministry said.
There were 11 attackers and they were all killed, it said in a statement, as were nine Afghans.
The Taliban warned last month they would step up their action this year, targeting government officials as well as the Afghan and international forces trying to thwart the extremist threat that is also growing in Pakistan.
The insurgency has steadily escalated over the past seven years forcing US President Barack Obama to announce in February a new strategy in Afghanistan.
The plan will see Washington deploy an extra 21,000 US troops to the impoverished and largely rural country, and puts pressure on Pakistan to deal with the militant sanctuaries on its soil.