American pilots dropped the controversial incendiary agent napalm on Iraqi troops during the advance on Baghdad. The attacks caused massive fireballs that obliterated several Iraqi positions.

The Pentagon denied using napalm at the time, but Marine pilots and their commanders have confirmed that they used an upgraded version of the weapon against dug-in positions. They said napalm, which has a distinctive smell, was used because of its psychological effect on an enemy.

A 1980 UN convention banned the use against civilian targets of napalm, a terrifying mixture of jet fuel and polystyrene that sticks to skin as it burns. The US, which did not sign the treaty, is one of the few countries that makes use of the weapon. It was employed notoriously against both civilian and military targets in the Vietnam war.

The upgraded weapon, which uses kerosene rather than petrol, was used in March and April, when dozens of napalm bombs were dropped near bridges over the Saddam Canal and the Tigris river, south of Baghdad.

"We napalmed both those [bridge] approaches," said Colonel James Alles, commander of Marine Air Group 11. "Unfortunately there were people there ... you could see them in the [cockpit] video. They were Iraqi soldiers. It's no great way to die. The generals love napalm. It has a big psychological effect."