Hurricane Gustav swept across the Gulf of Mexico yesterday, forcing the mandatory evacuation of New Orleans, the shutdown of offshore oil production and the cancellation of most of the programme on the first day of the Republican convention. About 1.9m residents of coastal Louisiana, including 200,000 from New Orleans, had left their homes by last night, said Bobby Jindal, Louisiana governor. Roads were jammedas they fled the danger zone, headed for Mississippi, Alabama and Texas. The storm was expected to make landfall today on the Gulf Coast at the category three level, with winds of up to 130 miles per hour and a storm surge reaching 12 feet - a slight improvement over earlier forecasts that it could reach category four. But US officials warned that Gustav could still be damaging enough to rival hurricane Katrina, which flooded most of New Orleans in 2005, plunging the city into chaos, killing 1,800 people and shaking US confidence in the Bush administration. Most of the crude production in the region - which accounts for a quarter of US oil output - was shut down and companies including ExxonMobil, BP, Chevronand Royal Dutch Shell evacuated thousands of workers. In an effort to smooth trading, electronic dealing at the New York Mercantile Exchange opened earlier than usual yesterday to allow betting on the hurricane's impact on energy prices. Oil rose to $118.60 but eased back to $117.13 by mid evening, up 1.5 per cent on Friday's close. Traders were divided on the impact of the hurricane as severe damage could be compensated for by the release - as in 2005 - of emergency oil and products stocks from US and other western nations' strategic reserves. Meanwhile, Republican preparations for the convention to nominate John McCain as their presidential candidate were upended. The first session was due to begin today at 3pm in Minnesota but will only include basic bureaucratic procedures. "[The] programme will be business only and will refrain from any political rhetoric," said Rick Davis, McCain campaign manager, adding that the future schedule would depend on the severity of the storm. George W. Bush, US president, and Dick Cheney, vice-president, were both scheduled to speak today but cancelled their appearances. Mr Bush plans to oversee the federal response to the crisis from response centres in Austin and San Antonio, Texas today. After visiting emergency operations in Mississippi yesterday Mr McCain said: "I have every expectation that we will not see the mistakes of Katrina repeated." Barack Obama, Democratic nominee, said his campaign was co-ordinating with local authorities and planned to mobilise supporters to volunteer or send money to help the relief effort.