Briefing the National Assembly's defence committee on the circumstances surrounding Basson's re-employment in the SANDF as a civilian, Kasrils said there had been some concern about Basson's expertise from his involvement in South Africa's chemical biological warfare defence programme.
At the time of his early retirement in March 1993, he had been the country's foremost scientist in its CBW defensive programme.
His co-operation was also necessary in several areas, including national intelligence, the office for serious economic offences, the auditor general and the truth and reconciliation commission.
South Africa had become signatory to various international non-proliferation treaties and had a responsibility to control and stabilise his life as best as possible because government could not simply assume that the secrets he knew were common knowledge in other countries.
Some 23 senior members of the old SADF had been given early retirement at the same time on the basis of the original Steyn report, which Kasrils said was a "file" rather than a report.
It contained notes, letters and other correspondence and made many allegations but had no factual evidence.
However, not a single charge had been brought against any of them as a result of the report, and at least three had been reinstated after vehemently denying allegations made against them in the report.
Further investigation into the allegations was necessary, he said.
The application to re-employ Basson as a civilian doctor in the cardiology unit at 1 Military Hospital had been approved by the public service commission in September 1995 and he had started work the next month.