CIA director Leon Panetta has confirmed seven agents have been killed in a bomb attack in Afghanistan.
Neither their names nor the details of their work were issued.
A bomber wearing an explosive vest entered a US base in Khost Province, near Pakistan on Wednesday.
The Taliban said the suicide attack was carried out by a member of the group working for the Afghan army.
The Chapman base is reportedly used by provincial reconstruction teams - which include soldiers and civilians - and is protected by some 200 Afghan soldiers.
It is also reportedly used for US drone attacks on suspects in Pakistan.
Earlier reports said eight people had been killed in the attack - the worst against US intelligence agents since 1983.
According to the Washington Post newspaper, a total of 90 CIA personnel have been honoured for their deaths in the agency's service since its inception in 1947.