Defying international appeals for clemency, Nigeria's military rulers hanged playwright Ken Saro-Wiwa on Friday, along with eight other anti-government activists.

The White House, European governments and human rights groups reacted with outrage. President Nelson Mandela of South Africa and British Prime Minister John Major demanded that Nigeria be kicked out of the 52-nation Commonwealth of Britain and its former colonies.Saro-Wiwa, 54, was convicted in the deaths of four men during a May 1994 political rally. He maintained that he was framed because of his opposition to the military regime of Gen. Sani Abacha and to the oil industry that earns 80 percent of Nigeria's export income.

"This heinous act by the Nigerian authorities flies in the face of appeals by the world community for a stay of execution," Man-dela said Saturday in Auckland, New Zealand, where the Commonwealth was meeting.

The United States recalled its ambassador to Lagos and broadly extended a ban on granting visas to Nigerians.

"The United States deplores the gravely flawed process by which Mr. Saro-Wiwa and his associates were convicted and executed," a White House statement said.

An ethnic Ogoni, Saro-Wiwa campaigned on behalf of the 500,000 Ogoni who live in Nigeria's oil-rich south and say their land and water are being destroyed by oil industry pollution.

A recent nominee for a Nobel Peace Prize, Saro-Wiwa received Sweden's $250,000 Right Livelihood Award last year and the Goldman Prize from a San Francisco foundation this year, recognizing him as one of Africa's leading environmentalists.

He wrote plays, children's books and two novels critical of the military government - "Sozaboy," the story of a cab driver who finds himself in the army, and "Prisoner of Jebs," which poked fun at the ruling elite.

Saro-Wiwa also wrote and produced a popular television series, "Basi and Co." which satirized the rich and famous, as well as the government.

A tribunal in the southern Nigerian oil city of Port Harcourt convicted Saro-Wiwa and the other eight men, all Ogonis, of murder on Oct. 31. The ruling military council upheld the death sentences Wednesday.

The men's wives tried to bring them a meal late Thursday but were turned away.

"What am I going to do? He is the only thing I have in the whole world," sobbed Hauwa Saro-Wiwa, the playwright's wife.

On Friday, with a large crowd of sympathizers gathered around her home, she told reporters: "It is all over."

The men were executed at about 11:30 a.m. and taken for burial inside the Port Harcourt cemetery, which was surrounded by armed soldiers and tanks. The junta announced the executions eight hours later and released no details.

Commonwealth leaders were holding talks Saturday on how to deal with Abacha, who seized power in a 1993 coup. Some have suggested imposing sanctions such as those used against South Africa's former apartheid regime.

The Clinton administration and the 15-nation European Union both said they were planning to review ties with the former British colony.

The Ogoni Community Association, an organization based in Britain, urged the United Nations to expel Nigeria.

"Although the dictator has had his day, we will win," said the association's president, Lazarus Tamana. "The memory of these men of peace lives on in all Ogoni. We will struggle for justice until we have won our rights and our share of the resources of our land."

At the United Nations, Secretary-General Boutros Boutros-Ghali said he was "shocked and appalled" to learn of the execution.

The environmental group Greenpeace said Saro-Wiwa's "blood will permanently stain the name of Shell," the oil company accused of despoiling the Ogoni territory.

A subsidiary of Royal Dutch Shell was driven out of the Ogoni region in 1993 when activists protesting damage by oil spills to rivers and crops sabotaged $30 million worth of equipment. Royal Dutch Shell is based in the Netherlands and London.

According to the human rights group Amnesty International, the other eight executed men were Barinem Kiobel, Saturday Dobee, Paul Levura, Nordu Eawo, Felix Nuate, Daniel Gbokoo, John Kpuinen and Baribor Bera.

"Nigeria has silenced one of its most effective critics, and we urge world leaders to maintain their pressure on Nigeria," the human rights group said.

Saro-Wiwa also served as the vice chairman of the Unrepresented Nations and People's Organization, a group based in the Netherlands that represents small ethnic groups.

Nigeria's foreign minister, Chief Tom Ikimi, defended the decision to execute Saro-Wiwa.

"He was responsible along with others for the gruesome murders of four of the members of that movement who were the original leaders," Ikimi said.