"The problem is, Dr Basson always had a choice and he did not exercise his choice in support of medical ethics," apartheid victims support group Khulumani director Dr Marjorie Jobson said in Pretoria.

"In theory he can say his activities did not have lethal consequences. As a doctor working in casualty departments in township hospitals [during apartheid] I saw the lethal consequences of the teargas and other agents."

Jobson said the level of Basson's transgressions required a heavy sanction.

"It is only out of the reality of sanctioning this behaviour that there is any reflection on what their [perpetrators] caused on citizens of South Africa. Mr [Eugene] de Kock is a prime example.

"We have come to realise that sanction creates the opportunity for reflection and for accepting responsibility. Without it, we never get to a point where people consider that perhaps their activities were not in the best interest of the country and the majority of the people," said Jobson.

De Kock was head of a covert police unit that tortured and killed dozens of anti-apartheid militants.

Basson's lawyer Jaap Cilliers SC asked if Jobson was appealing to the hearing to pass a harsh sentence so that the cardiologist would show remorse.

Jobson said a punitive sentence would be fitting for Basson.

"Everywhere in the world where I go, the first question which arises is 'how is it possible that Dr Basson has never been sanctioned up to now'. People cannot comprehend that," she said.

"We believe that his practice needs a very severe sanction. The problem is Dr Basson has not conceded, he has not shown that he has reflected on the possibility that he violated medical ethics. He has not taken responsibility."

She insisted Basson's claims that his activities were non-lethal, were dubious.

"Khulumani has a membership of 6800 families of the disappeared [people] who were abducted in operations by the security police using agents. There is no accountability yet about those activities," said Jobson.

Cilliers said there had been no evidence indicating his client's activities were lethal.

"The fact is, there is no suggestion in evidence that Dr Basson ever caused harm to anybody. Do you accept that there is no link between any harmful consequences and the conduct of Dr Basson," said Cilliers.

Jobson responded: "I accept that it was not possible to prove that beyond reasonable doubt. I have personal experience of the harms that people suffer because of the use of teargas and other agents."

Basson's HPCSA sentencing hearing began on Wednesday. In December last year the HPCSA found Basson guilty of unprofessional conduct.

The inquiry was held to determine whether Basson acted unethically in the exercise of his duties as a chemical warfare expert during the apartheid era.

He was accused of acting unethically by being involved in the large-scale production of Mandrax, cocaine, and teargas, of weaponising teargas, and of supplying it to Angola's then Unita leader Jonas Savimbi.

He was also accused of acting unethically by providing disorientating substances for cross-border kidnappings, and by making cyanide capsules available for distribution to operatives for use in committing suicide.

In 2002, Basson was acquitted by the High Court in Pretoria of criminal charges arising from his conduct.

The State appealed against this decision in the Supreme Court of Appeal but the appeal was dismissed.

The State then went to the Constitutional Court but the case was dismissed in September 2005.

The HPCSA reviewed the judgment to establish if there were grounds to continue with an inquiry.

The hearing resumes in January.