BP blames equipment failure for massive spill

Lamar McKay told ABC's This Week that he could not say when the well a mile beneath the sea might be plugged. But he said he believes a dome that could be placed over the well is expected to be deployed in six to eight days.

The dome has been made and workers are finishing the plan to get it deployed, Mr McKay said. He said BP officials were still working to activate a "blow-out preventer" mechanism meant to seal off the geyser of oil.

"And as you can imagine, this is like doing open-heart surgery at 5,000ft, in the dark with robot-controlled submarines," he said.

Crews have had little success stemming the flow from the ruptured well on the sea floor off Louisiana or removing oil from the surface by skimming it, burning it or dispersing it with chemicals. The churning slick of dense, rust-coloured oil is now roughly the size of Puerto Rico.

Adding to the gloomy outlook were warnings from experts that an uncontrolled gusher could create a nightmare scenario if the Gulf Stream current carries it towards the Atlantic.

Long tendrils of oil sheen have made their way into South Pass, a major channel through the salt marshes of Louisiana's south-east that is a breeding ground for crab, oysters, shrimp, redfish and other seafood.

A small group of fishing vessels this morning sailed through the marshes of coastal St Bernard Parish in eastern Louisiana, heading for the Biloxi Wildlife Management area. The oyster and shrimp boats, laden with boom, hoped to seal off inlets, bayous and bays.

There is growing criticism that the government and BP should have done more to stave off the disaster, which cast a pall over the region's economy and fragile environment.

But moving to blunt criticism that the Obama administration has been slow in reacting, Homeland Security Secretary Janet Napolitano told Fox News Sunday that the government has taken an "all hands on deck" approach to the spill.

She said that as BP officials realised more oil was spewing than first thought, the government had co-ordinated federal, state and local resources with the oil company's response.

Meanwhile, interior secretary Ken Salazar told NBC's Meet the Press that it could take three months before workers

attain what he calls the "ultimate solution" to stopping the

leak – drilling a relief well more than three miles below the ocean floor.

The April 20 explosion of the Deepwater Horizon exploration rig killed 11 workers, and what caused the blast remains unknown.

The Coast Guard and BP have said it is nearly impossible to know exactly how much oil has gushed since the blast, although it has been roughly estimated the well was spewing at least 200,000 gallons a day.

Even at that rate, the spill should eclipse the 1989 Exxon Valdez incident as the worst US oil disaster in history in a matter of weeks. But some experts warn the situation may already be much worse.