KABUL - A suicide bomb attack on US troops north of Kabul Tuesday killed an unknown number of US soldiers and three Afghan civilians, military and Afghan officials said.

The attack occurred in Kapisa province, where US and French troops have been deployed as part of the NATO-led International Security Assistance Force (ISAF).

An ISAF official told AFP on condition of anonymity that reports he had received said four US soldiers had been killed.

The US military and ISAF officially confirmed there were casualties among the troops but could not say how many.

'A suicide car bombing has happened and the target was an international forces convoy,' Afghan interior ministry spokesman Zemarai Bashary told AFP.

'The initial report we have received says three civilians were killed and three wounded.' Bashary could not give any information about the foreign troops. -- AFP