A US Marine general warned on Thursday that insurgents in Fallujah had only days to turn in their weapons, complaining that what was handed over so far was a load of 'junk'.
His angry statement came after a day marked by gun battles that marines say left 36 insurgents dead in the volatile town west of Baghdad.
Wednesday's violence also threatened a shaky cease-fire whose conditions include the hand over of heavy weapons by the insurgents.
"We were not pleased at all with the turning-in that we saw yesterday," commander of the 1st Marine Expeditionary Corps Lieutenant General James Conway said.
He characterised the weapons handed over as "junk, junk I think that I wouldn't begin to ask my marines to fire. It probably wouldn't be safe".
Asked how long the insurgents had to hand over their weapons, Conway said: "days, not weeks."
He said he believed there were at least 200 foreign fighters inside Fallujah. "We think they are the hard core and have been the catalyst for the vast majority of the troubles in Al-Anbar province." "What happens next is in the hands of the negotiators," he said, questioning whether they had the power to deliver?
"As we entered the negotiations with the prominent people around the city, we had every hope ... that they could argue reasonably for a peaceful solution. They said today we're somehow questioning if they represent the people of Fallujah ... because it's our estimate that the people of Fallujah have not responded well to the agreement that we made."
But a spokesman for the Sunni clerics, who have been involved in the negotiations, claimed US forces compliance with the cease-fire agreement was unsatisfactory.
Muthanna Hareh Dari claimed the Americans "fabricate pretexts to put pressure on the population".
Wednesday morning's battle started when up to 60 insurgents attacked US marines with small arms and rocket-propelled grenades in north-west Fallujah, the US-led coalition said in a statement.
"Marines responded to the attacks with overwhelming small arms and mortar fire, as well as close-air support, killing 36 anti-Iraqi forces," it added.
The military said earlier three marines were wounded in the battle.
A coalition official said the clashes on Wednesday were "very intense but very localised" and that the marines were honouring the cease-fire. "It would appear there is some honouring on both the sides."
The return of the families who fled the fighting was again suspended on Thursday because of tension in the city.
An armoured column of about 1,000 soldiers from the 1st Battalion 16th Infantry Regiment reached the outskirts of Karma on Thursday, a small village six kilometres north of Fallujah, in an attempt to clear food delivery routes from Baghdad to US bases to the west, according to an AFP correspondent at the scene.
According to the coalition, an attempt to clear the route last week met with fierce fighting that left 100 insurgents and one US soldier killed.
US bases west of Baghdad started rationing food from Sunday because of dwindling supplies caused by insurgent attacks.
US troops were also searching homes outside Fallujah on Thursday and Marine Corps helicopters were seen flying overhead.