A bomb killed four civilians in a crowded part of the Afghan capital on Sunday, security sources said.

The attack happened opposite a clinic on a road often used by foreign troops, one said, adding four more civilians were wounded.

There were no immediate word about casualties among the foreign forces, he said. The site of the attack was cordoned off.

A spokesman for the NATO-led International Security Assistance Force (ISAF) said they were aware of the incident but had no details immediately.

The blast took place just two days before dozens of foreign ministers -- including U.N. Secretary General Ban Ki-moon-- were due in the capital for an international conference of Afghanistan's future.

Some 150,000 foreign troops are squared off against Taliban fighters.
 

Reuters