As the chances of a low-pressure system in the Gulf of Mexico turning into a tropical depression in the next two days increase and reach around 70 percent, major oil and natural gas companies functioning in the U.S-regulated areas of the Gulf of Mexico have stopped their operations and started evacuating their employees.

BP Plc started evacuating its workers from its Mad Dog, Holstein, Atlantis, Nakika, Pompano, Horn Mountain, Marlin and Thunder Horse platforms. The company was also shutting down production at all of its eight oil and natural gas platforms located in the Gulf of Mexico.

Similarly, Anadarko Petroleum Corp has also evacuated its non-essential staffs from three of its platforms -- Gunnison, Nansen and Boomvant. A statement issued by the company said it was prepared to shut down production and evacuate all its employees if necessary.

According to a Bloomberg report, Diamond Offshore is evacuating the jack-up rig Ocean Titan and non-essential staff from two other Gulf rigs.

About 200 people will be evacuated today and tomorrow, the report quoted company's Director of Investor Relations as saying.

Thirty-one percent of U.S. oil output and seven percent of natural gas production comes from the Gulf of Mexico.

The National Hurricane Center upgraded Storm Katia to a Category 1 hurricane early Thursday morning. The storm is about 1,700 miles southeast of Bermuda, moving northwest. By Tuesday, Sept. 6, it is expected to be about 600 miles south of Bermuda and about 500 miles east of the Bahamas, the Christian Science Monitor reported.

Forecasters said Katia could eventually strengthen into a major Category 3 hurricane with winds over 110 miles per hour. However, the storm is still too far out to predict whether it will hit land at all, much less whether it will affect the United States or how bad it might be if it does.

Katia formed off the Cape Verde Islands in the eastern Atlantic Ocean on Tuesday, and it immediately got East Coast residents' attention as they coped with the severe flooding that Hurricane Irene brought to some areas over the weekend. Vermont and New Jersey were particularly hard-hit, and President Obama planned to visit New Jersey to assess the damage.