Protesters march to Jena High School in Jena, Louisiana, 20 Sep 2007

A judge in Jena, Louisiana has denied a request to release an African-American teenager whose arrest in the beating of a white classmate sparked a large civil rights protest in the southern U.S. state.

The court in the small town refused Friday to allow Mychal Bell to post bail while an appeal is being reviewed. He was convicted of aggravated battery and given a 15-year sentence for the December incident, but an appeals court overturned that conviction last week.

Bell is one of six black teenagers initially charged with attempted murder for the beating. The charges against at least four of the teenagers were later reduced.

Thursday, thousands of protesters from across the United States gathered in Jena to draw attention to what they say is racist treatment of those black students. Civil rights leaders say the treatment highlights lingering racism in southern states and in the judicial system.

The fight took place after months of racial tension between blacks and whites at school.

The beating incident stems from an occurrence in August last year, when a black student expressed interest in sitting under a tree in a school courtyard where only white students generally sat. Soon after, white students hung nooses from the tree's limbs, recalling white-on-black lynching during the early 20th century.

School officials called the noose display a prank and briefly suspended the students responsible. The local prosecutor said he did not charge the students accused of hanging the nooses because he could not find a Louisiana law that forbids the action.