When he was here at Harvard last year as a Nieman fellow, Percy P. Qoboza, editor of the black South African community's largest newspaper, said he did not worry about his government's reaction to his candid statements against apartheid during his stay in the U.S.

"The South African government will be loathe to bring the spotlight of unfavorable publicity on the country when I return," he said.

Qoboza may have been too optimistic. On Tuesday he was detained for eight hours by the South African police. Among other things, the police wanted to know the whereabouts of a black student leader whom Qoboza's paper, The World, had just interviewed.

Seven members of The World's staff were arrested in the police action, and four reporters remain in jail under laws that permit detention without trials, the New York Times reported yesterday.

Qoboza's newspaper, owned by whites but run almost entirely by black reporters, has generally retained a moderate nonviolent stance, although it opposes South Africa's program of apartheid.

"One has to make a choice whether to be outspoken and go to jail where you'll be silenced, or to take a milder platform so you can keep working," he said last year.

The 38-year-old editor enjoys a wide reputation as one of the South African black community's leading moderates. Last year, he stressed that "The whites are in South Africa to stay--we've got to devise some way by which we can all work together."

But since June, when he returned to Soweto--a black township outside Johannesburg--Qoboza's paper has taken increasingly vocal opposition to the government's policy of racial segregation, although The World has continued to advocate change through nonviolence.

Like Qoboza, Khotso Seatloho, the 19-year-old president of the Soweto Students Representative Council sought by the police, espouses nonviolent steps for change, The New York Times reported.

This summer, however, the Times said that Seatholo's group took a leadership role in the riots that flared in Soweto last June.

Qoboza told the police he does not know Seatholo's whereabouts, the Times reported yesterday.

During the entire eight hours he was kept at the police station yesterday, Qoboza was forced to remain standing. Qoboza, who suffers from high blood pressure, visited his doctor soon after his release, the Times said.

A senior officer of the South African security police said during Qoboza's retention that the interrogation was only for a routine questioning. "We want to talk to him about information he may have on what will happen in the country," another officer apparently told a World reporter.

When the police entered Qoboza's home--the police told reporters that the raid took place around 5 a.m., but Qoboza's wife Anne claimed that the time was closer to 3:30 a.m.--they searched his house for books banned from the country by the South African government.

Among the books examined were textbooks Qoboza used while attending courses during his stay at Harvard, his wife told a Reuters reporter.