A massive oil spill in the Gulf of Mexico resulting from a deepwater oil rig explosion has escalated into an environmental calamity as three U.S. states declared a state of emergency and President Barack Obama was forced to order "a thorough review of this incident" on Friday.

U.S. President Barack Obama on Friday ordered investigation into an oil rig explosion that led to a massive oil spill in the Gulf of Mexico, threatening fragile coastal environment there. [Xinhua]

The oil slick on Friday began washing onto Louisiana shores, a region known as the prime spawning ground for fish, shrimp and crabs. Lousiana produces most of the shrimp that goes onto dinner tables around the world.

President Obama on Friday said he had asked Interior Secretary Ken Salazar to "conduct a thorough review of this incident" and report back to him in 30 days on measures that will help prevent such a disaster from being repeated.

The White House also put new domestic offshore oil drilling on hold and sent teams to the Gulf coast to inspect all deepwater rigs and platforms to deal with safety concerns.

The states of Alabama and Mississippi followed Lousiana to declare a state of emergency as the oil slick edged closer to their coasts.

"This oil leak poses a serious threat to our environment and economy," Alabama Governor Bob Riley said in a statement. "With our natural resources, our businesses and our coastal communities in harm's way, Alabama can't afford to take anything for granted."

Mississippi Governor Haley Barbour has asked the National Guard to help with emergency response as a disaster loomed.