JOHANNESBURG, JUNE 19 -- The South African government today stepped up its pressure on Anglican Archbishop Desmond Tutu for remarks attributed to him saying that he would give the signal when he felt violence was necessary to end apartheid.

Minister for Law and Order Adriaan Vlok, in the sharpest attack yet on the 1984 Nobel Peace laureate since he made the controversial speech Tuesday in Mozambique, publicly asked Tutu whether he had discussed South Africa's "destruction" with Mozambican President Joaquim Chissano.

Vlok's question, posed at a police graduation ceremony in Pretoria today, followed confirmation by a police spokesman that an investigation is under way to determine whether Tutu had broken any law in the speech in Maputo, the Mozambican capital.

Vlok said he wanted to know whether there is freedom of religion in Marxist-ruled Mozambique, and added, "The task of any cleric is, after all, the development of Christianity. Bishop Tutu, did you negotiate about this with Mozambique's head of state? Or did you discuss the destruction of a country -- through violence -- where there is still freedom of religion?"

Vlok's remarks were reminiscent of a series of government attacks against the outspoken archbishop last year when, during a trip abroad, he called for punitive sanctions against South Africa.

A spokeswoman for Tutu said today the archbishop was visiting rural areas of Mozambique and could not be reached to respond to either Vlok's challenge or to South African press reports that he had promised to signal the start of antigovernment violence.

Meanwhile, one of two major press freedom cases in South Africa concluded today with the conviction of the Eastern Province Herald newspaper and one of its former reporters on charges that they had violated the Police Act by publishing allegations about security force actions in 1985 without reasonable grounds for believing them to be true.

Jo-Ann Bekker, the former Herald reporter, and the Times Media Ltd., owner of the Herald, were given suspended $100 and $50 fines, respectively, upon their conviction in a Port Elizabeth court of charges that the newspaper wrongfully published a report alleging that police had fired tear gas into a church.

The president of the court, G. Steyn, ruled that some of the statements in the newspaper report were untrue, and that none of three tear-gas canisters fired into the air to disperse a crowd outside had entered the building, although tear gas was blown inside.

The case had been watched closely by the publishers of South Africa's English-language newspapers, who have maintained that the police are attempting to harass them out of business with costly litigation. A similar case is pending against a reporter for the Cape Times.