Bowie said the donation was a "small gesture"

One of the teens, Mychal Bell, was found guilty of second degree battery in June by an all-white jury before the case was overturned by an appeal court.

The court said Bell, 16 at the time of the alleged incident in December 2006, should not have been tried as an adult.

Five others face charges. Bowie said Jena's judicial process was "unequal".

"A donation to the Jena 6 Legal Defence Fund is my small gesture indicating my belief that a wrongful charge and sentence should be prevented," said the 60-year-old in a statement published on his website.

The other students accused are Robert Bailey, 17, Theodore Shaw, 17, Carwin Jones, 18, and Bryant Purvis, 17.

A fifth teenager was booked as a juvenile and charges have not been made public

Racial tensions

The National Association for the Advancement of Colored People (NAACP), which is supporting the group's defence case, said it was pleased Bowie had got involved.

"We are gratified that rock star David Bowie was moved to donate to the NAACP's Jena campaign," said Julian Bond, chairman of the organisation's board of directors.

"Mr Bowie shares our outrage. We hope others will join him," he added.

Thousands are expected to march in protest through the small town of Jena on Thursday.

The Reverend Al Sharpton has helped organise the march and will later visit Mr Bell, who remains in jail because he cannot raise the $90,000 (£44,900) bail money.

The alleged assault followed a series of racial incidents between black and white students which began at Jena High School last summer.

A black student asked the school's principal whether he was permitted to sit under the shade of the school courtyard tree, a place traditionally reserved for white students only. He was told he could sit where he liked.

The following morning, when the students arrived at school, they found three nooses dangling from the tree.

The school's head recommended the noose-hangers be expelled but the governing board overruled him and the three white student perpetrators were briefly suspended.