A South African king is set to go to jail after the country's highest court threw out his bid to overturn a 12-year prison sentence.

Buyelekhaya Dalindyebo was convicted of kidnapping, assault and arson.

The Constitutional Court's rejection of his appeal bid means he has no option but to report to prison, says the BBC's Pumza Fihlani in Johannesburg.

King Dalindyebo comes from the Thembu ethnic group, to which anti-apartheid icon Nelson Mandela belonged.

He is the first monarch to be given a jail term since apartheid ended in 1994, and South Africa became a democracy.

The case was related to a dispute he had with some of his subjects more than two decades ago.

King Dalindyebo was accused of kidnapping a woman and her six children, setting their home on fire and beating up four youths, one of whom died, because one of their relatives had failed to present himself before the kings's traditional court.

"His behaviour was all the more deplorable because the victims of his reign of terror were the vulnerable rural poor, who were dependent upon him. Our constitution does not countenance such behaviour," the Supreme Court of Appeal said in a judgement in October.

"We are a constitutional democracy in which everyone is accountable and where the most vulnerable are entitled to protection," it added.