Hurricane Gustav bore down on the US Gulf Coast on Sunday with New Orleans firmly in its sights after leaving wreckage through western Cuba, weather officials said. ( dpa )
The "large tropical cyclone" was 520 kilometres south-east of the mouth of the Mississippi River, where the city of New Orleans is located. Winds were 195 kilometres an hour, making it a Category 3 storm on the Saffir-Simpson Scale, down from the Category 4 of just hours before.
But weather officials said that Gustav's forward movement had slowed as it gained strength from the warm Gulf waters, and anticipated it would again reach Category 4 or even greater by the time it makes landfall by noon local time (1500 GMT) or earlier.
Coming just three years nearly to the day that Hurricane Katrina buried New Orleans with a flood surge and killed 1,800, city residents were heeding Mayor Ray Nagin's mandatory order to evacuate. Tens of thousands were headed north in private vehicles, or were being picked up by city officials and delivered at bus and rail evacuation hubs.
US President George W Bush, who was heavily criticised for federal delay in aiding tens of thousands stranded in 2005, cancelled his plans to speak at the opening of the Republican presidential nominating convention on Monday in St Paul, Minnesota.
He planned to fly to Texas on Monday to see how relief preparation efforts were going.
In broadcast remarks, he pleaded with residents to cooperate with Nagin's evacuation order. "Do not put yourself in harm's way or put rescue workers at unnecessary risk," Bush warned.
Bush said the storm could bring "dangerous high winds" and noted that while the storm levees had been strengthened since 2005, "a storm of this size (carries) serious risk" of flooding.
Vice President Dick Cheney was also to have spoken at the convention, but those plans could change, broadcast reports said. First Lady Laura Bush would likely remain on the agenda, although Republican officials were also concerned about going ahead with the convention at all at a time when disaster loomed over an American city.
Senator John McCain, who is to be nominated the Republican Party's presidential candidate at the Monday-to-Thursday gathering, was headed on Sunday to the Gulf Coast to see first-hand the storm preparations, reports said.
Weather officials anticipated an "extremely dangerous storm surge" of four to five metres above normal tidal levels when Gustav's centre crosses the northern Gulf Coast. Gustav could also push a one-metre high storm surge against the Dry Tortugas, the chain of islands off the Florida Keys.
Mayor Nagin doubled the police and rescue presence in New Orleans and warned looters they would be taken immediately to the "big house" jail, referring to the Louisiana State Penitentiary, or " Angola." In 2005, many looters were held in local jails and released soon afterwards due to the chaos in the unprepared city.
In 2005, residents refused the call to evacuate because the storm was headed for landfall away from the city and out of fear their homes and businesses would be looted. What devastated the city was the storm surge that broke levees and inundated lower-lying areas.
This time, the storm was headed squarely to the city of 300,000, weather officials said.
Meanwhile authorities in Cuba on Sunday were moving to assess damage and allow evacuees to return to their homes. Gustav swept through the western part of the island on Saturday.
According to reports by the state-run Cuban News Agency (ACN), more than 250,000 people were evacuated from their homes in four western provinces and island regions on Friday and Saturday as the storm approached. No fatalities have yet been reported.