Mark Thatcher, the son of former British prime minister Margaret Thatcher, was arrested today over claims that he was involved in a plot to overthrow the government of Equatorial Guinea.
South African police said Thatcher was arrested at his home in Cape Town.
Spokesman Sipho Ngwema said he was expected to be charged with violation of the foreign military assistance act.
Mr Ngwema said: “We have evidence, credible evidence, and information that he was involved in the attempted coup.
“We refuse that South Africa be a springboard for coups in Africa and elsewhere.”
Thatcher is expected to appear in court later today.