The lawyer for the family of black nationalist Steve Biko charged today that there had been a coverup of the cause of his death in jail, and demanded that the inquest be expanded to discover who was responsible.

As the audience at the fourth day of the inquest murmured with excitement, lawyer Sydney Kentridge said that, if necessary, he would call as witness Justice Minister Jimmy Kruger. Pretoria's chief magistrate M.J.Prins, who is presiding at the inquest, is to rule Friday morning on Kentridge's request that he accept as evidence a dossier of public statements by Kruger about Biko's death.

The death of the nationalist leader Sept. 12 and later arrests of black leaders led to a U.N. arms embargo.

Counsel for the police, P.R. Van Rooyen contested Kentridge's request saying that Kruger's statements were "pure hearsay" because Kruger had not been in Port Elizabeth where Biko was jailed and could not qualify as a witness.

Prin's decision is a difficult one, since Kruger's remarks on Biko's death have been the subject of much controversy.

Kruger's original statement on Biko's death left the strong impression that he had died of a hunger strike.

"Since the fifth of September 1977, he refused his meals and threatened with a hunger strike," Kruger said the day after Biko's death. "He was however, regularly supplied with his meals and water which he refused to partake."

Later, Kruger clarified his remarks saying he never said a hunger strike was the cause of death. "I never suggested at any stage that Mr. Biko starved himself to death. I gave categorically the fact that he had gone on a hunger strike. That was given to me by the police. I never said that was the cause of death," Kruger said on Sept. 16:

Kentridge did not accuse Kruger of covering up the true cause of death. "The minister was misled. Who misled him, and why?" the lawyer asked.

"I fear we must go as far as to have the minister here himself and ask him to come and tell you(the magistrate) who gave him this false information," Kentridge said at one point.

Prins twice queried Kentridge about specifics, which led some observers in the audience to see Prins as reluctant to have Kruger on the witness stand. Prins initiated a length debate at one point on the exact meaning of the words "hunger strike," and implied that the police might have meant that Biko was just not eating because he wasn't hungry.

Later, Prins asked Kentridge if perhaps the hunger strike explanation had been the result of a "misunderstanding" and suggested that the line Kentridge was taking might be a "wild goose chase."

Kentridge dismissed the idea of a "misunderstand" and called the hunger strike story "entirely fabricated".

Public reaction in many circles to the hunger strike story was highly skeptical and it was contradicted by the official report on Biko's death which stated that he had died of head injuries. Kentridge argued today that unless it was established who started the hunger strike story, they would never get to the bottom of what happened to Biko in Port Elizabeth.

"If the security police give a false account, it can only be because they have something very serious to hide. Taken with other evidence, it would probably be the most competent evidence of all that something untoward happened," Kentridge said. Locating who in the security police was "planting false statements on the minister, "would give the inquest the "clearest indication of guilt," he added.

Both Col. P. J. Goosen, head of the security police in Port Elizabeth, and Maj. Harold Snyman, chief of one of the interrogation teams that dealt with Biko, have denied that they said Biko threatened a hunger strike.

Much evidence has been submitted to butress Kentridge's assertion that the hunger strike story was false.

A sworn statement from a prison hospital warder said that on Sept. 10 he fed Biko some porridge. On another occasion, he said, Biko was brought some water and a local brew called mageu , and Biko "wanted to kiss me he was so grateful."