The admission by the former Special Air Service officer, revealed in his autobiography Rules of Engagement, contradicts claims by the Ministry of Defence that the chemical was only ever used to create a smokescreen.

British troops also used white phosphorus to kill Argentinian troops during the Falklands conflict.

In his book, Col Collins describes how he trained 1bn Royal Irish Regiment for an attack codenamed Operation Fury planned for April 2003.

The colonel, who left the Army last year, said that he "directed" the men to "perfect" house-to-house fighting skills in preparation for the battle.

Discussing the weapons to be used in the operation in the Basra area, he wrote: "The star of the show was the new grenade which had only been on issue since the previous summer. It absolutely trashed the inside of the room it was put into.

"I directed the men to use them where possible with white phosphorus, as the noxious smoke and heat had the effect of drawing out any enemy from cover, while the fragmentation grenade would shred them."

Col Collins' tactics mirror the United States army "shake and bake" technique which involves forcing troops out of cover with white phosphorus and then killing them with artillery rounds.

The furore surrounding the weapon emerged last week after Lt Col Barry Venable, a Pentagon spokesman, used almost identical phraseology to Col Collins, when he confirmed that "shake and bake" was a recognised American tactic.

In an interview with the BBC, Col Venable said: "When you have enemy forces in covered positions that your high explosive artillery rounds are not having an impact on, one technique is to fire white phosphorus into the position because the combined effects of the fire and smoke will drive them out so that you can kill them with high explosives."

He confirmed: "It was used as an incendiary weapon against enemy combatants."

White phosphorus has been used by the British Army for decades to create instantaneous smokescreens during battle. In contact with skin, however, it burns to the bone and the gas it produces, phosphorus pentoxide, is poisonous.

Article two of Protocol Three of the 1980 Convention on Conventional Weapons bans the use of the weapon against civilians and also military targets located within civilian areas. Although the US is not a signatory of the convention, Britain is.

But there is now increasing debate as to whether the use of the weapon should instead fall under the United Nations Convention on Chemical Weapons.

Last week John Reid, the Defence Secretary, maintained the British troops had only ever used white phosphorus as a battlefield smokescreen. His department continued to stress that troops had never used it as "an incendiary weapon, against either civilians or even enemy combatants".

Although Operation Fury was cancelled, it remains unclear whether British troops went on to use white phosphorus against Iraqi forces, putting Col Collins' style of attack into action.

Prof Paul Rogers, of Bradford University's peace studies department, said he believed that most soldiers would use all weapons at their disposal.

He said: "There is a presumption among certain members of the population that wars are clean. They are not."Pentagon spokesman