Key committee and opposition parties object as minister says role might be unconstitutional.

Justice Minister Penuell Maduna's recommendation that the Heath investigating unit should take no part in the arms deal inquiry was condemned by a key parliamentary committee and a wide range of political parties yesterday.

The move heightened conflict between the cabinet and Parliament's public accounts committee, which has called for the unit's participation.

Committee chairman Gavin Woods yesterday expressed "disappointment", and said Maduna's reasons were questionable.

The Democratic Alliance, the Pan Africanist Congress (PAC) and the Inkatha Freedom Party attacked what they described as Maduna's failure to take account of Parliament's wishes.

In Pretoria yesterday, Maduna said it would be unconstitutional to draw Heath into the probe, following the Constitutional Court ruling that the judge must step down as unit head within a year. He restated the view of parliamentary speaker Frene Ginwala that a parliamentary directive to Mbeki to appoint the Heath unit would be of "dubious legal and constitutional validity".

He warned any move by the committee to set up a joint investigative body made up of the auditor-general's office, the public protector, the director of public prosecutions and the Directorate for Serious Economic Offences would have "no status in law". Such a body would not be able to compel witnesses to answer questions, and its subpoenas would not be enforceable.

Maduna said that in light of the serious allegations surrounding the arms deal, police commissioner Jackie Selebi and chief prosecutions director Bulelani Ngcuka had been asked to obtain "precise information" from the auditor-general's office and the committee so that a criminal investigation could be launched.

Insisting that government had received no evidence of wrongdoing, he said the Heath unit should provide such evidence to the police, on pain of "obstructing the ends of justice".

Woods said the committee had recommended the Heath unit's involvement because of its expertise and legal mandate. Its exclusion would leave a gap in the inquiry, and the committee would have to assess how to fill it.

Rejecting Maduna's assertion that Parliament had not requested Heath's involvement, he said the committee's report on the matter later adopted by Parliament had made its wishes clear. "The report said we needed a combined investigative initiative, and that we wanted exploratory talks with the four agencies."

Maduna seemed to have a poor understanding of the nature of the investigation. The auditor-general's special report and the committee's perception of weaknesses in the procurement process should have persuaded him.

Woods said Auditor-General Shauket Fakie and Public Protector Selby Baqwa had initially supported the Heath unit's involvement. If the Constitutional Court had felt the unit should have no more work in its last year under Heath, it should have said so.

Mbeki is expected to pronounce on the matter later this week. It is expected he will accept Maduna's advice.

Democratic Alliance leader Tony Leon said Maduna had become notorious for his bad judgment, and urged Mbeki to ignore his advice.

PAC MP Patricia de Lille said: "The investigation will stand or fall on the principles of transparency or accountability, which government is violating."

With acknowledgement to Farouk Chothia, Linda Ensor and Business Day.