A former leader of the American white supremacist group, the Ku Klux Klan, has been convicted of ordering the killing in Mississippi of a black civil rights activist more than thirty years ago.

The mixed-race jury found that Samuel Bowers, now aged seventy-three, had masterminded the firebomb attack on the home of Vernon Dahmer in 1966, which led to his death.

Prosecutors say Mr Dahmer had enraged the Klan by encouraging black people to register to vote.

The conviction carries automatic life imprisonment.

Four previous trials before all-white juries in the 1960s had failed to agree a verdict.

Samuel Bowers had previously served six years in prison for his involvement in the 1964 killing of three civil rights workers - Andrew Goodman, Michael Schwerner and James Chaney - the basis of the film Mississippi Burning.