At least 21 people have been killed after tornadoes tore through the central and southeastern United States.

Hundreds were injured when the twisters hit over the weekend, destroying homes, overturning cars and downing trees and power lines.

Authorities said 14 people died in Missouri, six in Oklahoma and one in Georgia as the storms tracked a course from the border of Kansas and Oklahoma on Saturday and into Georgia on Sunday.

Georgia authorities said earlier two had died in the state.

The path of destruction was a mile wide in some places, said Jason Schaumann, a meteorologist with the National Weather Service in Missouri.

"This looks like a very large tornado," he said. "We've got indications of cars that were thrown a quarter to a half mile, and frame homes that were swept off their foundations."

Damage indicated an EF3 tornado, which would have estimated wind speeds of 136 to 165 mph, he said.

Hail the size of softballs and wind gusts of 80 mph were also reported in Missouri, where 85 people were injured, authorities said.

Officials said six people were killed in the small northeastern Oklahoma town of Picher.

Local television footage showed homes ripped from their foundations, trees stripped of leaves and sheet metal twisted like paper.

"Basically a 24-block area is virtually destroyed," said Michelann Ooten, a spokeswoman for the Oklahoma Department of Emergency Management.

Oklahoma Governor Brad Henry ordered National Guard troops to help with rescue and recovery.

Picher is at the centre of a massive federal clean-up of pollution from lead and zinc mining. Residents were being assisted with relocation from the community after high levels of lead were found in groundwater.

President George Bush has offered prayers for families of those who died and said a day the country celebrates as Mother's Day was, for some, a sad occasion.

"The federal government will be moving hard to help. I'll be in touch with the governors and offer all the federal assistance we can," Mr Bush said before boarding Air Force One at Waco, Texas.

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