Ferocious Hurricane Gustav has moved into the oil-rich Gulf of Mexico where it is expected to strengthen and threaten New Orleans. The Category 4 storm cut a swath of destruction through western Cuba in a matter of hours and now poses a threat to Gulf oil fields on a projected path that could take it ashore near New Orleans, still recovering from Hurricane Katrina in August 2005. Forecasters said Gustav's winds had dropped to 140mph crossing the island, but, like Katrina, it could swell into a catastrophic Category 5 storm, with winds above 155mph, as it surges across the Gulf's warm waters. New Orleans officials, mindful of the 1,500 dead and more than £40 billion in damage wrought by Katrina, ordered people in the low-lying city to evacuate. Mayor Ray Nagin said: "I must tell you, this is the mother of all storms. "You need to be concerned and you need to get your butts moving and out of New Orleans right now." Highways around New Orleans are jammed and hundreds of people, some still carrying emotional scars from the disaster three years ago, lined up to board buses. New Orleans resident Leaura Landis's home was washed away. She said the family are leaving the area again: "It's hard to believe it's happening again. This was just how it was in Katrina ... We joked that we would all be back home in three days, but we came back three years later." Energy companies, whose 4,000 platforms in the Gulf produce a quarter of US crude oil and 15 per cent of its natural gas, braced for Gustav by evacuating personnel and shutting down three-fourths of their oil production. Planalytics analyst Jim Roullier said: "This storm will be more dangerous than Katrina. "I think this storm will prove to be a worse case scenario for the production region." When the storm hit Cuba it knocked over trees, damaged buildings, demolished banana plantations and, on the Isle of Youth, washed boats ashore, but no deaths had been reported.