James C. Thomson, curator of the Nieman Foundation for Journalism, said yesterday that Qoboza's detention will cause shock and outrage among his many friends and admirers in the American press community, in universities and in government circles.

"He is a true South African patriot who is deeply committed to the achievement of social and political justice for all the people of his nation, regardless of their color," Thomson said.

Benjamin Pogrund, an associate editor of South Africa's leading white liberal paper who spent six months working for The Boston Globe this year, said this fall that most newspaper censorship in South Africa has been internal. Members of the press must clear stories the regime considers either controversial or anti-apartheid with government representatives.

Pogrund was unavailable yesterday for comment about Qoboza's arrest.

The South African government does not insure freedom of the press, but can arbitrarily decide whether a newspaper has overstepped its privileges. Rather than face law suits and possible detention, Pogrund said, most papers prefer to take moderate stands.

Alex L. Boraine, a fellow at the Center for International Affairs who will return to South Africa tomorrow to take up his seat in the South African parliament, yesterday called the arrest "a very ominous sign."

Boraine, a member of the anti-apartheid Progressive Reform Party, said that the government has issued threats over the last few months that unless the press performed more self-censorship, the regime would crack down on all newspapers.

Until now, Boraine said, the press's relative freedom to openly criticize the government in editorials has provided "the only bright light in a very dark situation."

Nieman Curator Thomson, who has followed events in South Africa closely since his visit there last year, yesterday agreed with Boraine's evaluation of Qoboza's arrest. He called it "a serious escalation of the government's effort to intimidate the press."

Boraine called the arrest "a sign that the government is prepared to be more and more repressive in its effort to retain its dominance."

Under the apartheid system, about 4 million whites hold total control over the political system that governs a population of about 25 million.

But Boraine said he sees the situation in South Africa changing, as blacks begin to fight back. In the last six months, he pointed out, the Soweto students have shown willingness to die for their stand against apartheid.

This conviction "indicates the kind of situation they have been living in," he said.