Khost was hit by several suicide attacks on Tuesday
A suicide car bomb explosion near a US military base in eastern Afghanistan has killed seven civilians and wounded several others, the US military says.
The attack took place near the eastern town of Khost. Most of the casualties were believed to be local labourers working at the base, Camp Salerno.
There are no reports of casualties among coalition forces.
Khost was struck by several suicide blasts on Tuesday which left up to nine Afghans dead.
Meanwhile, the US military in Afghanistan says its forces mistakenly killed two civilians and wounded four others as they responded to an insurgent attack also in the east of the country.
The provincial police chief in Khost, Abdul Qayoum Baqizoi, confirmed that Wednesday's attack was a car bomb.
US military official, Specialist April Campbell, quoted by the AFP news agency from the main US base at Bagram, north of the capital Kabul, said: "Twenty-one local nationals were wounded and seven were killed."
Local officials said the toll of dead and injured could rise.
A man claiming to be a local member of the Taleban claimed responsibility for the attack.
The blast comes a day after nine people were killed in simultaneous attacks on government buildings in Khost.
On Tuesday, a spokesman for the militants, Zabihullah Mujahid, said: "Thirty of our fighters armed with suicide cars, suicide jackets and guns have entered the city."
Officials have not been able to confirm the number of militants involved.
Khost has witnessed frequent clashes between coalition forces and the Taleban.
In recent months militants have carried out attacks targeting several locations simultaneously, a sign of their increasing sophistication, analysts say.
Meanwhile, the US forces said they used air strikes in eastern Paktika province after insurgents fired rockets at two frontline military bases.
They said two civilians and six insurgents were killed.
A spokesman for the US forces said they regretted the loss of civilian lives and were investigating what had happened.
The issue of civilian casualties has caused tension between the authorities in Afghanistan and the international forces.
Last week, Afghan President Hamid Karzai said some 130 civilians were killed in US air strikes in the west of the country during fighting with insurgents.