Kabul: The FBI is conducting its own probe into the deaths of six Americans citizens who were among eight foreigners gunned down in northeastern Afghanistan in an attack claimed by the Taliban, a US official said Monday.
A US Embassy spokeswoman in Kabul said the FBI has opened an investigation in "cooperation" with local authorities and is weighing up repatriating the bodies to the US for post-mortems to be carried out.
"Under federal law, the FBI has jurisdiction to conduct investigations worldwide when US citizens are killed," spokeswoman Caitlin Hayden said in a statement.
"Plans have not been finalised by the families and authorities involved, but one of several possibilities is returning the remains of the deceased US citizens with dignity to the United States for autopsies."
The Afghan interior ministry initially said it was conducting the investigation.
The move to call in FBI investigators follows mounting anger and condemnation on Monday after the seven foreign aid workers and a film maker were shot dead in Badakhshan province on Friday.
Five US men and three women -- an American, a German and British doctor Karen Woo -- and two Afghans were killed in the attack. The group`s driver, survived.
The volunteers worked for the Christian aid group International Assistance Mission (IAM) but US officials and the charity denied Taliban claims that they were proselytisers and spies. The 10 bodies have been flown back to Kabul.
"The Taliban has proudly claimed responsibility for this despicable act of wanton violence," US Secretary of State Hillary Clinton said.
"We are heartbroken by the loss of these heroic, generous people," she said.
"We also condemn the Taliban`s transparent attempt to justify the unjustifiable by making false accusations about their activities in Afghanistan."
British Foreign Secretary William Hague said the killings were a "deplorable and cowardly act".
The Taliban and militant group Hizb-e-Islami claimed responsibility for the attack, which the interior ministry said was the work of "terrorists".
"We sent a team there to investigate who exactly did this," Lieutenant General Mirza Mohammad Yarmand, head of the ministry`s crime investigations department, told AFP.
The driver, Saifullah, had been spared apparently by reciting Koranic verses to the gunmen and is being questioned by interior ministry officials, IAM`s executive director Dirk Frans told reporters.