Simon Mann, the purported leader of a mercenary group accused of plotting to overthrow the government of Equatorial Guinea, was sentenced to seven years in prison in Zimbabwe Friday on weapons charges. Most of the rest of the suspected mercenaries were sentenced to spend a year in prison for breaking immigration and aviation laws.

Judge Mishrod Guvamombe said Mr. Mann, a former British soldier, was the mastermind behind the group's alleged mercenary activities, and sentenced him to seven years, without chance of appeal.

The saga began in March, when an aircraft with 67 South Africans, mostly former soldiers, touched down in Harare allegedly to pick up weapons bought from the Zimbabwe government's defense industries. They were arrested, and Mr. Mann and two colleagues, who were already in Zimbabwe, were detained as they were inspecting the arms before they were to be loaded onto the plane.

The two pilots who flew the plane to Zimbabwe from South Africa were sentenced Friday to 16 months in prison.

The suspected mercenaries all claimed they were on their way to guard a mine in the Democratic Republic of Congo. The governments of Zimbabwe and Equatorial Guinea say the men were part of a plot to oust the government in Malabo.

Two men were acquitted of all charges in Zimbabwe and returned to South Africa two weeks ago, where they are being questioned by prosecutors in connection with alleged violation of laws, which ban mercenary activity.

The case also pulled in Mark Thatcher, son of Britain's former prime minister, Margaret Thatcher. Mr. Thatcher, who is living in Cape Town, is accused by South African prosecutors of helping finance the ill-fated mission.

Most of the group are poor blacks from Angola and Namibia, who had no jobs after they left the South African Defense Force ahead of democratic elections in 1994.

After the trial ended, David Coltart, legal secretary for the opposition Movement for Democratic Change in Zimbabwe, said mercenaries are a blight on Africa. He said the men had been better treated in comparison to what many Zimbabweans have endured in detention. He also said the trial was concluded more speedily than most cases.

Another 14 men are on trial in Equatorial Guinea, in connection with the same case. One of them, Nick du Toit, a business associate of Simon Mann's, is facing the death sentence there, if found guilty as charged.