A man who says he is the son of former DR Congo President Laurent Kabila has been charged in South Africa with plotting to overthrow the government of Joseph Kabila.Etienne Taratibu Kabila is alleged to be the leader of 19 other people who were charged last week.Etienne Kabila says President Kabila is not the true son of Laurent Kabila.His claims about the president and to be the former leader's son have been dismissed by DR Congo's government.Etienne Kabila handed himself in to police at the weekend.He was not asked to enter a plea and the case was postponed until Thursday, when his case will be joined to that of the other 19.Prosecutors said they belonged to the Democratic Republic of Congo's Union of Nationalists for Renewal (UNR) rebel group.South Africa's counter-terrorism forces arrested them last week in the northern Limpopo province under the country's Foreign Military Assistance Act, which is intended to crack down on mercenary operations in the country.DR Congo has been hit by numerous rebellions throughout Joseph Kabila's rule.He took power in 2001, after the assassination of Laurent Kabila and has since won two elections.