Mr Clinton appealed for the community to join across racial lines to reaffirm that America would not tolerate this kind of incident.

BBC US correspondent Malcolm Brabant: "Hallmarks of a lynching"

Three white men with links to white supremacist groups have been charged with killing 49-year-old James Byrd as he walked home from a niece's party. The murder has shocked the US.

The three accused - Laurence Brewer, 31, and Shawn Berry and John King, both 23 - are said to have driven Mr Byrd to a remote spot, where he was beaten and chained to the back of a pick-up truck.

He was then dragged behind the truck for 3km with such violence that he was decapitated and his right arm severed, according to an affidavit of probable cause released by police.

Berry: "KKK ties" says sheriff

The BBC Washington Correspondent says that even in a country grown used to lurid accounts of murder, this crime stands out.

Jasper County District Attorney Guy James Gray said: "It was real brutal and real serious. It's a senseless murder."

A tool engraved with the name of one of the suspects was found near the body.

All three suspects are tattooed with symbols of Aryan Nation - a white supremacist group.

James Byrd's sister, Clara Taylor, talks of her shock at his death

Jasper County Sheriff Billy Rowles says they have also all spent time in prison where they had ties to the Ku Klux Klan. But he insists there are no white supremacist groups operating in Jasper, 160km north of Houston.

If the men remain charged with murder the maximum sentence is life. But federal investigators are examining the case to see whether the killing amounts to a hate crime which would warrant a capital murder charge and a potential sentence of death by lethal injection.

Our correspondent says they can expect little judicial mercy if convicted, as Texas is proud of its reputation for executing more convicted killers than any other state in the US.