South Africa denied a passport to a University of Natal professor invited to address a Smithsonian Institution lecture series here last Monday, and Smithsonian officials said yesterday they fear that a black South African labor leader scheduled to appear next week also will be refused travel documents.

South African officials ignored a request for a passport from Fatima Meer, a sociology professor and antiapartheid activist in Durban, forcing a last-minute cancellation of her appearance, according to Meer and Smithsonian employees.

"I'll tell you what is the very rude aspect of this particular application," Meer said yesterday in a telephone interview from Durban. "It is that until now they have not even bothered to inform me that they were not granting the passport."

Meer, who has been banned and imprisoned in the past for antiapartheid activities, said U.S. Ambassador Edward Perkins personally had taken up her travel request with a Cabinet minister.

Next Monday night's scheduled speaker, Cyril Ramaphosa, general secretary of the 300,000-member National Union of Mineworkers, also had not been told yesterday whether his request for a passport to address the series would be granted, the Smithsonian said.

Coenraad J. Bezuidenhout, a spokesman for the South African Embassy here, said he was aware of the invitations for Meer and Ramaphosa but did not know the outcome of their passport requests.

The 10-week lecture series, entitled "South Africa Today: Life in a Divided Society," is sponsored by the Smithsonian and Howard University. Meer was scheduled to speak on "The Anatomy of Violence in South Africa," and Ramaphosa's topic is "Life in the Mines."

Three speakers have appeared as scheduled in the series: Shula Marks, a white South African historian who holds a British passport; American music historian David Coplan, and Andre Brink, an Afrikaner writer. South African journalist Allister Sparks substituted Monday night for Meer.

Meer said she was told Friday that the government had not decided whether to issue her a passport, meaning she could not depart last weekend for the United States.