A judge sentenced a Czech criminal who is already being held at South Africa's most secure prison to 35 years in jail.

In televised proceedings on Tuesday, Judge Colin Lamont sentenced Radovan Krejcir, along with five other men, some of them former policemen.

Krejcir, representing himself, asked for leave to appeal his conviction and sentence. Armed police stood guard inside the courtroom and the Czech remained chained throughout proceedings because of security concerns. A day before, the courtroom was cleared after a bomb threat.

Krejcir was convicted last year for kidnapping, attempted murder and drug dealing. He was arrested in 2013 for kidnapping a man whose brother disappeared with 25 kilograms (55 pounds) of the drug crystal methamphetamine that authorities said was supposed to be smuggled through Johannesburg's airport.