A white university lecturer who was nearing the end of a five-year banning order imposed because of his opposition to government policies was slain and a former member of the suppressed African National Congress was shot in separate incidents in Durban early this morning.

Richard Turner, a political philosophy professor at the University of Natal, was killed by a shot fired through his bedroom window and died in the arms of his 13-year-old daughter, Jann.

Less than an hour before, Stephen Mtshali was gunned down by an assailant with a silk stocking pulled over his face. Mtshali is in critical condition at a Durban hospital, according to the South African Press Agency.

Police are investigating the possibility that the two shootings are linked, the agency said.

The death of Turner, 36, has prompted some people here to warn of what they fear is an emerging pattern of assassination attempts against both critics and supporters of the government's policies of racial separation.

"It's very distressing," said Prof. Lawrence Schlemmer, one of Turner's colleagues at the university. "There are signs that [South Africa] will resemble the Northern Ireland situation.

"One thing we always had going for us in South Africa up to now was that the system has been fairly predictable. Though actions were arbitrary, they were formal . . . But as tension is increasing [in our society], informal groups are starting to take action outside any kind of legal, political, organizational framework."

Zulu chief Gatsha Buthelezi, a major leader in the struggle for black political power, visited the Turner home this morning. Reached tonight he said he thought a pattern of assassination attempts was becoming apparent and he found it "very ominous."

Last month a guest in the home of a banned sociology lecturer, Fatima Meer, was wounded as shotgun blasts ripped through the front door. Shots were also fired in June at the home of banned newspaper editor Donald Woods, who fled the country last month. Under South African law, persons who are "banned" are placed under a form of house arrest that isolate them from outside contacts by varying degrees according to the value of the banning order.n September, the home of detained editor Percy Qoboza was the target of a gasoline bomb.

These are referred to here as "right-wing" terrorism. But there also have been incidents of "left-wing" terrorist assaults. In September last year, a black security policeman, a "reformed terrorist," was shot to death in his bed at his Durban home. In June, two Johannesburg men were killed in a garage by three black youths wielding automatic pistols. And a few months ago two policemen were wounded in a gunbattle with a black schoolteacher in a Johannesburg suburg.

Police have reported no solution to these or many similar cases, the majority directed at critics of the government.

"I think it was an assassination," said Turner's mother, Jane, reached by phone at her son's home.

According to Mrs. Turner, her son and his two daughters, Jann, 13, and Kim, 9, were asleep when they were awakened by a noise outside the front door about 12:30 this morning. When he opened the bedroom window to investigate, he was shot and died instantly, Mrs. Turner said.

Turner, described as "one of the most brilliant professors at the University of Natal," received his doctorate at the University of Paris. He was the author of a radical critique of Western democracy.

In 1973, he and seven others were put under a five-year banning order after an investigation of their activities with the National Union of South African Students. Turner was a faculty adviser to the student group. His banning order was due to expire next month, but he believed that it might be renewed, according to a friend.

Available information on Mtshali was scanty. He was described by the South African Press agency as a former terrorist and member of the military wing of the African National Congress who turned state's evidence and testified in terrorist trials against the accused. Government critics have often charged, however, that state's witnesses are testifying under duress in many cases.

According to police, Mtshali was at his home just outside Durban, when a man drove up and called for Mtshali to accompany him. When Mtshali refused, the assailant opened fire, police said.