US expects Gulf oil slick to hit land tomorrow

(Chris Graythen/Getty Images)

Senior Obama administration officials said on Thursday a widening oil spill in the US Gulf Coast will come ashore tomorrow evening and that it may take 90 days to shut off the oil leak valve.

Briefing reporters at the White House, the officials described the spill as being of national significance and said the government will push BP Plc as hard as possible to stop the leak and lead the cleanup.

It could be 90 days before a relief valve is installed to stop the leak, the officials said.

"The spill is now crossing different regions," said Homeland Security Chief Janet Napolitano. "We will continue to push BP to engage in the strongest response possible.

Coast Guard Rear Admiral Sally Brice O'Hare said the oil slick is expected to hit the Gulf shoreline on Friday evening.

Interior Secretary Ken Salazar has ordered an immediate safety review of offshore rigs, the officials said.

White House spokesman Robert Gibbs said the administration will be aggressive in its response to the leak, triggered by a deadly rig explosion that now threatens the shoreline of four Gulf states.

He said all available resources, including the possible use of the military, had been offered to combat the spill.

BP and the Coast Guard have already mounted what the London-based company calls the largest oil spill containment operation in history, involving dozens of ships and aircraft.

But they are struggling to control the slick from the leaking well 5,000 feet (1,525 metres) under the sea off Louisiana's coast, which the Coast Guard said late on Wednesday was spilling five times more oil than previously estimated.

Napolitano said the oil leak was distinct from the 1989 leak of oil from the Exxon Valdez tanker off the coast of Alaska, when 10.8 million gallons of oil spilled.

"The Valdez was a knowable quantity of oil because it was a ship. This is a well," she said.