US PRESIDENT Barack Obama will visit an oil spill area in the Gulf of Mexico in the next 48 hours to assess the situation and the US government’s response.Oil from a giant Gulf of Mexico slick began washing onto Louisiana shores on Friday, threatening an environmental calamity, as two more neighbouring states declared a state of emergency.With up to 757,000 litres of oil a day spewing into the Gulf of Mexico, the accident stemming from a sunken offshore rig may soon rival the Exxon Valdez disaster as the worst oil spill in US history.The Mobile Press-Register reported yesterday that the US Coast Guard now feared the underwater oil well could become an unchecked gusher shooting millions of litres of oil per day.Citing a confidential National Oceanic and Atmospheric Administration report, the Alabama newspaper said two additional release points had been found.”If the riser pipe deteriorates further, the flow could become unchecked, resulting in a release volume . . . higher than previously thought,” the paper quotes the report as saying.Earlier, Mr Obama said about 1900 federal response personnel were in the area with 300 boats and aircraft.The White House also put new domestic offshore oil drilling on hold until the disaster had been fully investigated. It has sent teams to the Gulf Coast “to inspect all deep water rigs and platforms to address safety concerns”.BP faces a slew of US lawsuits accusing it of negligence over the spill. The suits were filed as US government officials said that BP was responsible for cleaning up the slick and the British oil giant pledged to pay for “legitimate claims” stemming from the disaster.Two shrimp boat operators have filed a suit in New Orleans seeking class-action status on behalf of all Louisiana residents who live, work in or derive their income from the zone affected by the oil spill.Their suit alleges that the fire, explosion and resulting spill at the rig were “caused by the joint negligence and fault” of BP and other defendants.