A racial slur made in Parliament by a member of Prime Minister Pieter Botha's Cabinet has virtually assured that blacks will not cooperate with a council Botha has proposed to consider reforms in this segregated nation.

Hennie Smit, minister of posts and telecommunications, said yesterday that blacks will not be included on the proposed President's Council because they are "less developed" and have "slower thought processes" than whites. The comments were a major blow to what has been a tough government campaign to win support for the council, which will be charged with drafting a new constitution.

"This will make it imposible for any [leader to cooperate with the council]withdout being seen to be endorsing [that] view of us," Zulu Chief Gatsha Buthelezi said.

The 60-member President's Council, which Botha's supporters consider a reformist step. is to be made up of white, Colored (mixed race). Indian and Chinese delegates. Under the proposal, blacks will have a separate body, which will serve an advisory role. The plan has been rejected by most black, Colored and Indian leaders.

Apart from the exclusion of blacks, the exercise is being rejected because of the government has made it clear that any constitution it drafts will be based on the apartheid concept of an ethnically based geographic partition of South Africa.

Even the white opposition members of Parliament have refused to cooperate with the council. Helen Suzman today called it a "lifeless corpse that never had a chance of survival. By the omission of blacks it was stillborn."

"They are sick. He is sick," said black Anglican Bishop Desmond Tutu in reaction to Smit's comment. "It just shows the basis of their legislation. It's one more insult we've had to absorb.

"But if Africans are less developed and have a slower thought process, why then are whites afraid of competing with them on an equal basis?"

The minister of black affairs, Pieter Koornhof, who faces the task of persuading blacks to participate in the exercise, reportedly hung his head and appeared visibly shaken at Smit's statement.

"I know that the black man takes longer to decide on a matter than we do," Smit told Parliament after suggesting it was not "feasible" for blacks and whites to deliberate together.

Smit said today that his comment "wasn't an insult. I have never insulted people. I have a very proud record on not insulting people."