EMERGENCY crews rushed to protect fragile shorelines and islands as the Gulf of Mexico oil slick expanded, prompting a mobilisation of more national guard troops and alerts as far as the Florida Keys.

US President Barack Obama yesterday warned of “massive and potentially unprecedented environmental disaster” as a giant oil slick from the Gulf of Mexico threatens environmental and economic catastrophe.

A new oil leak was discovered at the site of the wrecked drilling rig in the Gulf of Mexico, with an estimated five times more oil spilling into the water every day than previously thought, the US Coastguard said today.

BP crews raced to protect the Gulf of Mexico coastline as a remote sub tried to shut off an underwater oil well gushing 42,000 gallons a day from the site of a wrecked drilling platform.