US President George W Bush has toured some of the areas worst hit by Hurricane Katrina and entered central New Orleans for the first time.
His third visit to the Gulf Coast comes as opinion polls show a deep dissatisfaction with his response to the disaster.
In comments during the tour, President Bush acknowledged that authorities may have relaxed before the worst effects of the Hurricane became clear.
But he angrily dismissed questions on alleged mismanagement and damage to his own reputation.
After arriving in the region last night, Mr Bush went to a base camp to greet hundreds of firefighters from around the US who had come to help. He then spent the night aboard a military ship docked near downtown New Orleans.
FEMA Director resigns under pressure
Federal Emergency Management Agency Director, Michael Brown, has resigned under fire for a slow response to Hurricane Katrina,
Brown was pulled out of Gulf Coast operations on Friday and recalled to Washington. President George W Bush has been under pressure from Democrats to fire him.
The resignation came three days after Homeland Security Secretary Michael Chertoff removed Brown from federal relief efforts in the Gulf Coast and sent him back to Washington.
During a visit to Gulfport, Mississippi, Bush was asked about Brown's resignation. He told reporters he had not talked to Brown or to Chertoff but said he would speak with the Homeland Security chief on the Air Force One flight back to Washington.
Death toll rises to over 500
There are indications that New Orleans is beginning to recover two weeks after Hurricane Katrina devastated the low-lying city and forced its half a million people to flee.
Water levels are dropping, in some areas by as much as two metres as more pumps are introduced to help drain the city.
In parts of the city the water service has been restored, electricity reconnected and fallen trees and branches cleared from the streets.
Local officials are turning their efforts to commerce, trying to restart an economy that powerful Katrina brought to a halt.
The total number of confirmed victims of the huge storm and flooding has meanwhile risen to over 500.
The current toll in New Orleans stands at 279 and another 214 have been confirmed dead in the stricken state of Mississippi.
