The car bomb exploded as a convoy was passing near a US-run military base, Camp Phoenix, that is focused on training the fledgling Afghan national army.

Taliban, which have carried out scores of similar attacks as part of a deepening insurgency, claimed responsibility for the blast in an SMS from the telephone of a known spokesman for the group.

Local police said one person was killed and four injured, three of them Americans. The dead man was a truck driver who had been passing by, he said.

The blast struck a convoy of the US-led occupation, the force said in a statement. It said three soldiers were wounded but did not give their nationality.

The NATO-led ISAF force, which works alongside the US-led occupation, said its information was that seven Afghan passers-by were wounded in the blast.

The last suicide blast in the capital was on July 18 and targeted Turkish soldiers with ISAF. A civilian passer-by was wounded.