LONDON — South African police Wednesday seized Mark Thatcher, the scandal-plagued son of former British Prime Minister Margaret Thatcher, on charges that he took part in a plot with mercenaries to overthrow the dictatorship of oil-rich Equatorial Guinea.
An anti-corruption Scorpions unit of the South African police raided Thatcher's luxurious villa in the posh Cape Town suburb of Constantia at 7 a.m., surprising the 51-year-old businessman and former race car driver in his pajamas.
Thatcher appeared before a magistrate and was put under house arrest and given until Sept. 8 to post bail of $300,000. His lawyer insisted that Thatcher was innocent and said he was cooperating with authorities.
A prosecutor said Thatcher faced a maximum penalty of 15 years in prison if convicted.
"We have evidence, credible evidence, and information that he was involved in the coup," police spokesman Sipho Ngwema said. "We refuse that South Africa be a springboard for coups in Africa and elsewhere."
Thatcher, who has a twin sister, Carol, has been in the headlines frequently -- seldom in a complimentary light -- since his mother became prime minister in 1979.
Over the years, he has been accused of trading on his mother's name and connections to become a multimillionaire in a series of murky business dealings. "Mark could sell snow to the Eskimos and sand to the Arabs," his mother once reportedly said of him.
But he is also remembered for a string of failed enterprises and for becoming hopelessly lost in the Western Sahara for six days during the 1982 Paris-Dakar rally -- an ordeal that caused his normally stiff-upper-lipped mother to weep publicly before he was located by search planes.
The younger Thatcher's reputation for trouble was such that in 1987, when his mother was facing reelection, her former press secretary, Bernard Ingham, had a curt piece of advice for how he could best aid in the campaign.
"Leave the country," Ingham said.
In Britain, news of Thatcher's arrest immediately prompted worries about how it would affect Margaret Thatcher, who is approaching her 79th birthday and whose health has been of concern since she suffered a series of minor strokes in recent years and endured the death of her husband, Denis, in June 2003.
Currently vacationing in the United States, and due to return to England on Friday, she had no immediate statement, a spokesman said.
Britain's first woman prime minister, known as the "Iron Lady" for her take-no-prisoners opposition to communism abroad and socialism at home, left office in 1991 after serving longer than any prime minister in more than 150 years. She was later given the title of baroness by Queen Elizabeth II. A confidant of President Reagan, she delivered a eulogy at his funeral 2 1/2 months ago.
Mark Thatcher is the neighbor in South Africa and close friend of Simon Mann, a former British special forces officer accused of leading an alleged attempted coup aimed at Equatorial Guinea's longtime strongman president, Teodoro Obiang Nguema Mbasogo.
Mann was arrested in Harare, Zimbabwe, with arms and 69 other men, en route to Equatorial Guinea.
Mann says the men and weapons were to provide security for an oil company, not overthrow the government and install a new president, as Obiang and the government of Zimbabwean President Robert Mugabe have charged. Officials in Equatorial Guinea allege a relative of the president had promised Mann and his alleged force of mercenaries a share of the West African country's oil riches if they helped topple Obiang.
In addition to those arrested in Zimbabwe, 18 men went on trial this week in Malabo, Equatorial Guinea's capital; there have been allegations that a 19th died under torture during the investigation.
The justice minister of Equatorial Guinea, Ruben Mangue, said the country would not seek Thatcher's immediate extradition. "Let's first give an opportunity to the South African authorities and the South African legal system to handle the situation," he said on BBC radio.
Thatcher's name surfaced in the case weeks ago after Mann appealed to him to help secure his release. A South African prosecution spokesman, Makhosini Nkosi, told BBC's Radio 4 that Thatcher may have been "involved in the funding of logistical support" for the suspected mercenaries.
Thatcher, who inherited the title of baronet when his father died, is married to Diane Burgdorf, the daughter of a wealthy Texas car dealer and has two children.
Police investigators ransacked his house Wednesday. Later, taken to a holding cell, he was set upon by fellow prisoners, who stole his jacket, shoes and mobile telephone, all later recovered, police said.
In an article in today's Telegraph, Charles Moore, Margaret Thatcher's authorized biographer, wrote of the deep mutual affection between the Thatchers and their son despite the embarrassment sometimes caused by his "chiaroscuro business career." "When Denis was ill, it was Mark who arranged the necessary convalescence in South Africa," Moore wrote.
"Now that he is dead, it is Mark who has his mother to stay to see the grandchildren and makes sure that she is properly looked after. His only fault in relation to her -- and hers in relation to him -- is an excess of zeal over judgment.
"If he has to spend her last years in a South African jail, her sense of sadness and loss will be immense."
Janet Stobart of The Times' London Bureau contributed to this report.