An oil leak from a destroyed rig causing an oil spill in the Gulf of Mexico is massive and potentially catastrophic, the U.S. Interior Secretary Ken Salazar said on CNN's "State of the Union" program.

"It potentially is catastrophic," Salazar said. "I think we have to prepare for the worst."

Salazar also said that "it is indeed a massive oil spill."

However, CNN reported Sunday citing the Coast Guard commandant, Adm. Thad Allen, as saying that the exact size of the leak still remains unknown.

"This spill, at this point in my view, is indeterminate," Allen said on CNN's "State of the Union." "That makes it asymmetrical, anomalous and one of the most complex things we've ever dealt with."

LA News Monitor said on Sunday the U.S. President Barack Obama was expected to visit the U.S. Gulf Coast to see with his own eyes a response to the enormous oil spill that is still growing and moving towards American shores.

The New York Times said on Friday, U.S. Coast Guard officials began investigating reports that oil hit the coastline in the early hours of Friday, posing a threat to nature on islands along the Gulf Coast.

A state of emergency was declared in Louisiana on Thursday as oil from the Deepwater Horizon rig, which sunk on Thursday, continues spilling out into the sea.

Emergency workers ignited on Wednesday some of the surface oil as part of a clean-up operation.

However, the oil slick still covers some 70,000 square kilometers (more than 28,000 square miles) of the Gulf's waters.

Obama pledged on Thursday to "use every single available resource" to avert larger damage. Some 6,000 U.S. National Guard troops were sent to the area of the disaster to help carry out clean-up operations.

An explosion which caused the oil spill ripped through the Deepwater Horizon, some 50 miles off the Louisiana coast, on Tuesday. The blast claimed the lives of 11 people who were working on the rig and injured other 17.

The accident, which is seen as a challenge to Obama's plans to build more oil rigs along the Atlantic shore, poses a major threat to the Gulf of Mexico's flora and fauna. The Gulf, which hosts some 4,000 drilling platforms, is home to many endangered animal species.

MOSCOW, May 2 (RIA Novosti)