New Orleans and Florida braced for new storm

Three weeks after Hurricane Katrina devastated his city, Ray Nagin said he was now concerned about the threat from Tropical Storm Rita. Under pressure from President George Bush and federal officials, Mr Nagin said he was choosing to be cautious.

"I am concerned about this hurricane getting in the Gulf [of Mexico] ... If we are off, I'd rather err on the side of conservatism to make sure we have everyone out," he said. "Now we have conditions that have changed. We have another hurricane that is approaching us."

The mayor warned that the city's pumping system was not running at full capacity, its levee system was still in a "very weak position" and that even a period of sustained heavy rain could be enough to see the floodwaters return.

Meteorologists said they expected Rita to develop into a hurricane with winds of at least 111mph as it drew strength from warm waters in the Gulf of Mexico after passing over the Florida Keys today.

Officials have ordered the evacuation of the Keys, and authorities in Miami-Dade County, location of the city of Miami, urged residents to evacuate mobile homes, barrier islands and areas prone to flooding.