The son of former British Prime Minister Margaret Thatcher has been arrested in South Africa for alleged involvement in a coup plot in Equatorial Guinea.

South African police say 51-year-old Mark Thatcher was arrested early Wednesday at his home in Cape Town. Mr. Thatcher, a businessman living in South Africa, is expected to appear in court later Wednesday.

A South African law enforcement official, Sipho Ngwema, says police are investigating allegations he helped finance the alleged coup plot.

A key defendant on trial in Equatorial Guinea testified Wednesday he met Mr. Thatcher, but said the meeting was only to secure a business deal.

Eighteen people, including 14 foreign suspects, are on trial in Equatorial Guinea. Seventy others are on trial in Zimbabwe in connection with the alleged plot.