Obama views tornado devastation

US president Barack Obama said he had "never seen devastation like this" as he viewed the wreckage left by tornadoes which killed almost 300 people in the US South.

The loss of life - with 297 dead, mostly in Alabama - is the greatest as a result of tornadoes in the US since April 1974, when the weather service said 315 people were killed by a storm that swept across 13 Southern and Midwestern states.

Mr Obama reassured survivors as he and first lady Michelle Obama walked through the streets of Tuscaloosa, saying: "We're going to make sure you're not forgotten."

The twisters left trees uprooted and houses demolished. One young man told Mr Obama he had witnessed debris lifting up all around him, yet he emerged with only cuts and bruises.

"It's a blessing you are here," the president told him.

Mr Obama's predecessor, George W Bush, was criticised for responding too slowly to another natural disaster, Hurricane Katrina, which battered and flooded New Orleans and other parts of the South in 2005.

The tornadoes death toll seems surprising in the era of sophisticated radar and precise satellite forecasts, but the power and width of the storms meant there was no way to avoid heavy casualties.

In one of its first official assessments of the tornadoes' strength, the National Weather Service gave the worst possible rating to one that raked Mississippi with 205mph winds, and said it was the strongest to hit the state since 1966.

The situation was dire about 90 miles to the north in the demolished town of Hackleburg, Alabama, where officials were keeping the dead in a refrigerated truck amid a body bag shortage. At least 27 were killed there, with searches for the missing continuing.

The fire and police departments have been destroyed, along with the school and the only food store. There is no power, communications, water or other services. Fire Chief Steve Hood said he desperately wants torches for the town's 1,500 residents because he does not them to use candles that could start fires.

"We don't have water to put out any fires," he said.

Elsewhere, drivers hunted for fuel for cars and generators after many petrol stations were shuttered by power outages.

As many as a million homes and businesses in Alabama are without power, with state governor Robert Bentley saying 2,000 National Guard troops had been activated to help. The governors of Mississippi and Georgia also issued emergency declarations for parts of their states.

The storms seemed to hone in on populated areas by hugging the interstate highways and obliterating neighbourhoods and even entire towns from Tuscaloosa to Bristol, Virginia.

Concord, a small town outside Birmingham, was so devastated that authorities closed it down to keep out the curious.

Some of the worst damage was in Tuscaloosa, a city of more than 83,000 that is home to the University of Alabama. The storms destroyed the city's emergency management centre, so the school's stadium was turned into a makeshift one.

Seventy-three-year-old Frank Frierson sat on a porch in Tuscaloosa and marvelled at the damage.

"It was God up there letting us now that he is the boss, what he could tear up and what he could destroy," he said.