(Corrects story to clarify that Exxon Valdez ran aground)
HOUSTON May 27 Mud on the lens of the camera providing video images of the pipe gushing oil into the Gulf of Mexico has blocked the view of the attempt to stop the spill, BP Plc (BP.L) said on Thursday.
There was no attempt attempt to prevent the public from watching efforts to plug the leak from the damaged well, a BP spokesman said.
"It's just operational," said BP spokesman Jon Pack. "The camera that was closest to the riser got mud on its lens".
Last week BP began broadcasting video images of its leaking underwater oil well, following pressure from U.S. Congressional leaders concerned about the lack of progress in halting what is now the largest oil spill in U.S. history.
Since then the images have focused on a plume of black crude oil flowing from a pipe, called a riser, which is connected to the well head. However, on Thursday all video has been of the equipment at the top of the well.
On Wednesday BP began its latest attempt to plug the well, in an operation dubbed "top kill", involving pumping heavy drilling fluid into the blow out preventer, a heavy piece of equipment that sits on top of the well. The goal is to stall the flow of oil with the heavy fluids and then pump concrete into the well to shut if off for good.
Some of the mud being pumped into the blow out preventer traveled up the riser, expanding the plume of leaking oil, and this was what obstructed the camera, Pack said. He said he was unaware if it would be possible to solve the problem and restore images of the leaking riser.
On Thursday BP said it was making progress on plugging the ruptured well as U.S. government figures showed the disaster has eclipsed the previous worst U.S. oil spill caused when the Exxon Valdez ran aground in 1989 and spilled 11 million gallons of oil into Prince William Sound [ID:nN26238003].
BP shares jumped 6.0 percent in London on the comments from BP and from the U.S. Coast Guard suggesting the flow of oil had already been restricted by the pumping of the drilling mud into the blow out preventer.
The success or failure of the latest operation to stop the oil spill will continue to move the company's shares, analysts at French bank Societe Generale said in a research note on Thursday.
The oil company is aware that traders are watching the live video link closely for signs that the operation has succeeded but has warned that images from the seabed will be an unreliable indicator of progress.
BP said at around 1800 CDT (2300 GMT) on Wednesday that it would take 24 hours to know if the latest operation had been a success. (Reporting by Tom Bergin in Houston)