The oil started to wash up in small inlets and cove areas, and forecasters said strong winds could push it into ponds and lakes over the weekend.

The slick, 200 kilometres long and 112 kilometres wide, threatens hundreds of species of wildlife, including birds, dolphins, shrimp, oysters and crabs.

With the wind blowing from the south, the mess could reach the coasts of Mississippi, Alabama and Florida by May 3.

Oceanographers say part of the slick could get caught in what's called the Loop Current, which flows through the Florida Straits and becomes the Gulf Stream.

If that happens, the stream of oil could be pulled through the Florida Keys and then northward up the state's eastern coast, fouling Atlantic beaches, within two weeks.

President Barack Obama will head to the Gulf Coast on May 2 to get an update on efforts to contain the massive spill, a White House official said Saturday.