Doctors in the hurricane-hit US city of New Orleans have warned of a "second disaster" if residents begin returning to the city before it is ready.
Flood waters are receding, but leaving mud-caked streets
Medics backed the view of Vice Admiral Thad Allen, head of the recovery effort, but contradicted advice issued by the city's mayor, Ray Nagin.
Mr Nagin has urged residents of some areas to return home this week.
But doctors warn that major disease risks remain, and Vice Adm Allen says the city stills lacks basic services.
"The second wave of disaster is when you welcome the people back and the infrastructure of the city is not in place," said Dr Peter Deblieux, a casualty specialist at a New Orleans hospital.
Vice Adm Allen said the mayor's plans to get 200,000 people back to their homes within the next 10 days were "extremely problematic".
He said services such as water, sewage, electricity and health care were not yet capable of supporting a large influx of people.
"If you bring significant amounts of people into New Orleans, you need an evacuation plan on how you're going to do that," he told US TV networks.
"The announcement to move the repopulation ahead of any of those completed tasks in our view puts the city at risk."
In a statement, Mr Nagin said: "We believe our re-entry plan properly balances safety concerns and the needs of our citizens to begin rebuilding their lives."
Reports said the pair plan to meet on Monday.
About 40% of the Louisiana city is still flooded.
The BBC's Claire Marshall in New Orleans says the displaced victims will be unsure which advice to follow.
Some business owners who have started to trickle back have said there is no custom for their enterprises.
"Everyone is anxious to come back and see if their place is OK," Kevin Molony, who runs a company conducting tours of the city, told AFP news agency.
The admiral (l) and the mayor have contradicted each other
"It's a ghost town. Tourism has been slammed."
Armed police and troops are continuing to patrol the streets in an effort to maintain security and prevent looting. A night time curfew remains in force.
In his weekly radio address at the weekend, President George Bush said the federal government would assume the bulk of the costs for "one of the largest reconstruction efforts the world has ever seen".
Congress has already approved $62bn for the recovery effort along the Gulf Coast, but costs are expected to total $200bn (£110bn).
Mr Bush has hinted at spending cuts elsewhere to fund the operation, but has ruled out raising taxes.
The president's approval ratings have slumped to 40%, the lowest of his time in office.