A suspected suicide bomber attacked a military convoy on the eastern outskirts of Kabul on Friday, killing at least three foreign soldiers, police and the NATO-led International Security Assistance Force (ISAF) said.
The Taliban claimed responsibility for the attack which comes as President Hamid Karzai deliberates over an agreement allowing US forces to stay in the country beyond 2014.
ISAF put the death toll at three service members.
The Slovak foreign ministry said two of the dead were Slovak servicemen and one was a US soldier.
A Taliban spokesman claimed responsibility in a message on his Twitter account.
"A number of foreign forces were killed and wounded and many vehicles were also destroyed," the militant spokesman said.
Many Afghans, including a gathering of 3,000 tribal leaders and other prominent people, have urged Karzai to sign the US pact quickly because they worry about security after 2014 when most foreign forces are leaving.
Karzai says he does not want to sign until after a presidential election scheduled for April next year and unless the United States fulfils a number of his demands.