Oil from the leaking Deepwater Horizon rig has started washing ashore, according to US reports.
US scientists from the National Oceanic and Atmospheric Administration said that the oil is leaking at the rate of 5,000 barrels a day, not 1,000bpd as originally estimated.
US President Barack Obama has pledged "every single available resource" to help and the US navy has been deployed to help avert a looming environmental disaster.
An explosion and fire on the drilling rig on 20 April left 11 workers missing, presumed dead. The rig sank two days later, about 50 miles off the Louisiana coast.