South African Prime Minister John Vorster today dismissed criticism of the verdict clearing South African authorities of responsibility for Stephen Biko's death as the comments of uninformed people and nations.

"I think it's highly improper for the State Department . . . to comment as they did," Vorster said of the U.S. Government statement that it was "shocked by the verdict in the face of compelling evidence at the least that Stephen Biko was the victim of flagrant neglect and official irresponsibility."

Vorster said that although a magistrate had absolved security officials of any blame for Biko's death while in detention, the possibility of civil actions remained and made it inappropriate for him to comment on the details of the case.

The Prime Mister's first remarks since the Biko verdict last Friday came in a live interview by satellite with Robert MacNeil and Jim Lehrer of the Public Broadcasting System.

Vorster displayed a lack of curiosity about the Biko case surprising in a head of government. He could not explain why Biko was kept naked or why Biko's brother was arrested as the verdict was announced, Vorster said, because he had not been personally involved.

Vorster's apparent indifference to criticism from other governments prompted Lehrer to ask whether he cares what people think of South Africa.

"Naturally I care what each and every man who knows something about my country says," the Prime Minister replied. "But if I must care about what uniformed people have to say about my country then I would have my work cut out for me just to keep abreast of what they're saying."

At another point, Vorster was asked what he thought of criticism by U.N. Secretary General Kurt Waldheim, members of the British House of Commons and the U.S. government, and he answered: "The people who know the least about the situation, they normally talk most about it.'

The prime minister said he was satisfied with the Biko verdict but added: "I am sorry that out of this very, very unfortunate incident so much propaganda was made . . ."

On Nov. 30, Vorster's government was re-elected with the largest parliamentary majority in the 67 year history of South Africa, 134 of the 165 seats. South African officials had indicated that after the expected landslide vote from the white electorate, the government would implement significant social reforms.

Vorster refused to discuss any forthcoming reforms. "My government has effected more changes in South Africa than all previous governments combined. It is a continuous process and as time goes on certain changes will be made," he said.

The prime minister repeated his criticism of Vice President Mondale for saying South Africa should have one-man, one-vote government. He said he finds it difficult to understand what the Carter Administration's policy toward South Africa is because of the number of statements made by U.S. officials.