Two leading human rights activists were arrested today in an official crackdown on those who have made allegations of abuses by the Zimbabwean government.

Michael Auret, chairman of the Catholic Justice and Peace Commission, was picked up this afternoon at its offices here by plainclothed policemen who searched the office and also seized a stack of papers.

Arrested at the same time was Nicholas Ndebele, the commission's director, who had just been released yesterday by a court order from a previous detention. Auret is white, Ndebele black.

Human rights advocates and western diplomats here said they believed the two men were arrested because they had supplied information to international rights groups such as Amnesty International and the New York-based Lawyers Committee for Human Rights.

Home Affairs Minister Enos Nkala, who is in charge of the police, has accused Amnesty, local church groups, western diplomats and journalists of conspiring to smear the government with allegations of rights abuses. In a recent press conference, he referred to church groups saying, "I might have to hammer them."

Minister of Information Nathan Shamuyarira said the government would have no comment on the arrests tonight, although it might issue a statement later.

Ndebele was first arrested two weeks ago, the day after the Lawyers Committee released a report accusing government security forces of engaging in "grave and persistent abuses of human rights" in southwestern Matabeleland, including murder, torture and abductions during periodic crackdowns against armed dissidents. Officials have denied the allegations.

"Coming just after the Lawyers Committee report, this is not just a simple attempt to harass the Justice and Peace Commission," said a legal analyst. "Nkala seems to be putting everyone on notice that they should not talk to foreigners or else."

The commission, an arm of the Roman Catholic Church here, has long been the country's foremost human rights group. It was a persistent critic of summary executions, mass detentions and torture that occurred in what was then Rhodesia under Ian Smith's white-minority government.

It has played a similar role since the advent of black rule in 1980, although it has consistently tempered its criticism with praise of Prime Minister Robert Mugabe's programs for education, health and rural development.

Auret and the commission have criticized government crackdowns in Matabeleland and last year he linked the mysterious disappearances of dozens of political opponents in that region to security forces.

He had recently returned from a four-week trip to the United States where he had commended Zimbabwe's black leaders for "carefully building a vibrant society and economy" and had called on the Reagan administration to increase its aid program here.

Police said the two men were being held on suspicion that they possessed unspecified "prohibited documents," according to the Rev. Patrick Moloney, a priest who witnessed today's arrests. Ndebele previously had been arrested on suspicion that he had given information to unnamed "enemy countries," according to court papers filed last week.

Lawyers for the men were said to be seeking an urgent court hearing Friday morning to ask for their release.

Ndebele was taken directly to Chikurubi maxium security prison here, while Auret was driven to his home in Chinhoyi, about 120 miles away, where police planned to search the premises.

Neither man was allowed to speak to reporters who watched as the two were taken away. But Auret was overheard telling colleagues at the office that "they're doing this because Nkala thinks I talk to Amnesty."

Auret's wife, Diana, in a telephone interview from their home, called his arrest "an incredible injustice." She noted that Auret had been an outspoken opponent of white-minority rule and in 1979 had left the country for a year of self-imposed exile in Britain.

"Mike has spent his entire life working for the good of this country," she said. "If all that counts for nothing then I don't believe Zimbabwe or even Africa stand a chance."

Diana Auret blamed Nkala for her husband's arrest, saying the police minister "has been gunning for Mike for some time."

At least a dozen people have been rounded up and held for various periods recently following the May 19 South African commando raid on two sites here linked to South African insurgents. A government source suggested tonight that the two arrests might be linked to the wide-ranging investigation of that incident. But other analysts said they believed the probe was only a pretext for these particular arrests.

The U.S. charge d'affaires here, Gibson Lanpher, expressed concern over the arrests and said the embassy would be following developments "closely."