Reports from Cape Town say Mark Thatcher, the son of the former British prime minister, is preparing to plead guilty on Thursday to violating South Africa's anti-mercenary laws in connection with an alleged coup plot in Equatorial Guinea.

Officials from the South African prosecutor's office and lawyers for Mr. Thatcher have confirmed that he will make a court appearance Thursday, but they refuse to say why.

Several British news organizations, including Sky TV News and The Times of London, are reporting that Mr. Thatcher has made a deal with prosecutors to plead guilty to unintentionally breaking South Africa's anti-mercenary law by giving money to the alleged coup plotters without knowing what it was for.

Sky and The Times say he will be sentenced to a suspended five-year jail term and a fine of around $500,000. The Times says he will be allowed to leave the country.

Mr. Thatcher was arrested in August and accused of helping fund a plot to overthrow the government of Equatorial Guinea. His close school friend, Simon Mann, has been convicted in Zimbabwe on weapons charges relating to the case and is serving a seven-year prison sentence there. Scores of other men, mainly from South Africa, Angola and Namibia, are serving year-long terms in Zimbabwe on related charges.

Another 19 men are on trial in Equatorial Guinea in connection with the alleged coup plot. Authorities there are seeking Mr. Thatcher's extradition. In November, the Cape High Court ordered Mr. Thatcher to answer a list of questions submitted by prosecutors from Equatorial Guinea, but his lawyers are appealing that verdict, saying it violates his right to avoid self-incrimination. It is not clear how the reported plea deal will affect that case.

In London, a spokesman for Mr. Thatcher's mother, former British Prime Minister Margaret Thatcher, says she is "relieved that matters have now been settled and that the worry of the last few months is over."