Oil giant British Petroleum (BP) succeeded on Thursday in cutting a portion of the pipe that is gushing oil into the Gulf of Mexico, in what the United States government officials described as a "significant step" in the ongoing effort to plug the leaking wellhead.

The next step is to place a small containment dome over the marine riser pipe, which could siphon oil up to the surface. But the cut is not as fine as was originally hoped, forcing BP to use a wider containment cap that might not capture all of the oil.

Coast Guard Admiral Thad Allen, who is coordinating the government’s response to the disaster, said the successful sheer cut was the first bit of good news in days and "a significant step forward at this point". Engineers, using robotic submarines operating at the ocean floor, will attempt to place the "top cap" dome over the pipe during the day on Thursday, Adm. Allen said.

Also on Thursday, the White House announced that President Barack Obama was planning another trip to the region on Friday, his third since the Deepwater Horizon rig explosion on April 20.