Prime Minister Robert Mugabe overruled a senior Cabinet minister late last night and ordered the release of two human rights activists arrested by police.

Michael Auret and Nicholas Ndebele, the chairman and director respectively of the Catholic Commission for Justice and Peace, Zimbabwe's foremost rights monitoring group, were freed after Auret's wife, Diana, phoned Mugabe to plead for their release. They were arrested yesterday afternoon.

In ordering the release, Mugabe overturned an arrest order from Home Affairs Minister Enos Nkala, a senior Cabinet member and the fourth ranking member of the ruling party's Politburo. Nkala's ministry oversees the police.

Western diplomatic sources said they could recall only two previous occasions when the prime minister had intervened to have political detainees released, and then he did so quietly. Last night's action was the first time Mugabe has openly reversed the arrest of a major public figure since Nkala launched a crackdown on opposition politicians and other government critics following Mugabe's landslide reelection victory last July.

"Auret was a big fish and a number of people in government were obviously appalled when they heard about his arrest," said a diplomatic analyst. "It seems like an individual minister got out of line and my guess is that things will cool off for a while."

The government has not made any statement on the arrest and release of Auret and Ndebele. Mugabe's press spokesman did not return phone calls today seeking comment.

Until now, the commission, a lay arm of the Catholic Church, Zimbabwe's largest denomination, was one of the few institutions of public dissent that had been allowed to function undisturbed by the government. It maintains an extensive network of priests and lay people who report to it on allegations of rights violations.

While it has maintained a cautious public stance, the commission has on occasion gone to court seeking the release of detainees when it believes they are being held illegally. Auret has spoken out strongly several times against alleged rights abuses.

Auret appeared at police headquarters here this morning for questioning about papers police had seized from his office yesterday. He later said at a press conference that his arresting officer had accused him and Ndebele of possessing "prohibited documents," a criminal offense with a penalty of up to five years' imprisonment. He said the officer never indicated what documents he was referring to.

Auret said he believed the real reason for his arrest was Nkala's belief that the commission had supplied information about allegations of police torture to Amnesty International, the London-based rights organization. Amnesty published a report in November citing "persistent accounts of torture" of detainees by police, including beatings and electric shocks.

Nkala has branded the report and a subsequent report by the Lawyers Committee for Human Rights in New York as lies and has repeatedly accused Amnesty of conspiring with local church groups, British and American diplomats, foreign journalists and even the CIA to smear Zimbabwe's international reputation.

Auret denied that he or Ndebele had provided information to Amnesty. Richard Carver, the organization's spokesman on African affairs, supported Auret's denial in a telephone interview.

"The intention of these kind of arrests obviously is to make people think twice about talking to us," said Carver.

Diana Auret said at the press conference that when she reached Mugabe by telephone last night the prime minister told her he had already heard about the arrests and had immediately ordered the releases.

"I said, 'Well, he's still sitting in the jail in Harare and nothing has been done about it'," Diana Auret recalled. "So he said, 'I will look into it immediately and do something about it.' And he appears to have done so."

Auret called her an hour later to tell her he had been released, she said. She said of Mugabe, who was educated by Catholic missionaries, "He's a good man. I believe he felt immediately that something had happened that he wasn't actually aware of."