In a week filled with dreadful scenes of desperation and anger from New Orleans following Hurricane Katrina some stories stood out.

But as time goes on many remain unsubstantiated and may yet prove to be apocryphal.

New Orleans police have been unable to confirm the tale of the raped child, or indeed any of the reports of rapes, in the Superdome and convention centre.

New Orleans police chief Eddie Compass said last night: "We don't have any substantiated rapes. We will investigate if the individuals come forward."

And while many claim they happened, no witnesses, survivors or survivors' relatives have come forward.

Nor has the source for the story of the murdered babies, or indeed their bodies, been found. And while the floor of the convention centre toilets were indeed covered in excrement, the Guardian found no corpses.

During a week when communications were difficult, rumours have acquired a particular currency. They acquired through repetition the status of established facts.

One French journalist from the daily newspaper Libération was given precise information that 1,200 people had drowned at Marion Abramson school on 5552 Read Boulevard. Nobody at the Federal Emergency Management Agency or the New Orleans police force has been able to verify that.

But then Fema could not confirm there were thousands of people at the convention centre until they were told by the press for the simple reason that they did not know.

"Katrina's winds have left behind an information vacuum. And that vacuum has been filled by rumour.

"There is nothing to correct wild reports that armed gangs have taken over the convention centre," wrote Associated Press writer, Allen Breed.

"You can report them but you at least have to say they are unsubstantiated and not pass them off as fact," said one Baltimore-based journalist.

"But nobody is doing that."

Either way these rumours have had an effect.

Reports of the complete degradation and violent criminals running rampant in the Superdome suggested a crisis that both hastened the relief effort and demonised those who were stranded.

By the end of last week the media in Baton Rouge reported that evacuees from New Orleans were carjacking and that guns and knives were being seized in local shelters where riots were erupting.

The local mayor responded accordingly.

"We do not want to inherit the looting and all the other foolishness that went on in New Orleans," Kip Holden was told the Baton Rouge Advocate.

"We do not want to inherit that breed that seeks to prey on other people."

The trouble, wrote Howard Witt of the Chicago Tribune is that "scarcely any of it was true - the police confiscated a single knife from a refugee in one Baton Rouge shelter".

"There were no riots in Baton Rouge. There were no armed hordes."

Similarly when the first convoy of national guardsmen went into New Orleans approached the convention centre they were ordered to "lock and load".

But when they arrived they were confronted not by armed mobs but a nurse wearing a T-shirt that read "I love New Orleans".

"She ran down a broken escalator, then held her hands in the air when she saw the guns," wrote the LA Times.

"We have sick kids up here!" she shouted.

"We have dehydrated kids! One kid with sickle cell!"