BP has said that crews lowered a 125-ton steel dome into the Gulf of Mexico, hoping it will contain oil leaking from a destroyed well at a rate of 5,000 barrels a day.

According to CNN, officials said that getting the four-story dome into place on the sea floor 5,000 feet below likely will take until at least Sunday.

Oil collected inside the dome is to be piped into a drill ship on the surface and, if it works, BP plans to use a second, smaller dome to cap another leak.

Authorities have said that as the slick of oil spread Friday across the northern gulf and washed ashore on Louisiana's barrier islands, the containment method has been used to clean up spills but never on any approaching this scale.

Adm. Thad Allen, commandant of the Coast Guard, said, "I think we're all hopeful that this will have an impact on this leak."

He said, "It's been done before, but never at these depths." The admiral said that it showed everything possible was being tried to stop the leak.

He said, "But this will be difficult."

The (New Orleans) Times-Picayune has reported that Scott Bickford, an attorney representing a rig worker, said BP and the drilling platform owner, Switzerland-based Transocean Ltd., began removing a mud barrier before a final concrete plug was installed, which experts said weakens control of a well in an emergency.

BP was trying to seal off an exploratory well when the explosion occurred April 20, leaving 11 workers missing and presumed dead.

The Times-Picayune also said that the oil giant declined to answer questions about how far along it was in the process of closing the wellhead below the Deepwater Horizon rig at the time of the blast. (With Inputs from Agencies)