Army Brigadier-General Yves Fontaine, commander of the 1st Corps Support Command, on Friday said the number of attacks along supply routes had grown to about 30 per week, although the US casualty rate has declined because extra protective armour has been installed on supply trucks and other vehicles in the transportation fleet.

Most of the attacks, he said, are in the region that extends north and west of Baghdad.

"We have seen an increase in the use of IEDs on our convoys," he said, using the military's acronym for improvised explosive devices, or roadside bombs.

"And our main threat is the IED for the logistics convoys coming from Kuwait, Jordan and Turkey, and then going to the Baghdad area."

Extra armour

More than 2000 supply vehicles have been given extra armour

Speaking in Washington at the Defence Department by a video link from his headquarters at Balad air base, north of Baghdad, Fontaine said more than 2000 supply vehicles have been given extra armour and that no vehicle is sent outside a secure base without armour.

"That's a good news story, as far as our up-armouring is concerned," he said.

"Because we have up-armoured our vehicles the casualties have decreased significantly even though IED attacks are increasing." He did not offer specific casualty figures.

Fontaine also said his force, which numbers about 18,500 soldiers based at five main hubs, has responsibility for helping the Iraqis develop their own military logistics system to sustain their combat forces.

So far, two of the three existing Iraqi motorised transportation regiments are capable of operating on their own, Fontaine said. The goal is to have nine or 10 fully independent Iraqi support regiments by this time next year, he added.