BP's chief executive is on his way to Louisiana as the worst US oil spill in decades spreads along the Gulf Coast.

Dr Tony Hayward's trip to oversee the emergency operation came as the oil giant was accused of downplaying the possibility of a catastrophic accident at the offshore rig that exploded on April 20.

The blast claimed the lives of eleven workers, but its full consequences remain to be seen, as the slick continues to spread, threatening the habitat of hundreds of species of wildlife in Louisiana.

US President Barack Obama is also planning to visit the Gulf of Mexico for an update on efforts to contain the spill. He is expected to arrive within the next 48 hours.

A BP spokesman said: "Dr Hayward is on his way over to Louisiana to oversee the operation, support the response and meet the people working hard over there. He is there to provide what support he can."

The US Coast Guard estimates that a devastating 1.6 million gallons of oil has spilled since the blast, creating a slick more than 130 miles long and 70 miles wide.

Although the cause of the explosion was under investigation, many of the more than two dozen lawsuits filed in the wake of the blast claim it was caused when workers for oil services contractor Halliburton improperly capped the well - a process known as cementing. Halliburton denies the accusation.