Opposition parties are up in arms about President Thabo Mbeki's exclusion of Judge Willem Heath's Special Investigating Unit from the R43-billion arms deal probe.

The Pan African Congress said it would continue with its court action against the government for ruling against parliament's decision.

The Inkatha Freedom Party said it feared the possible repercussions for South Africa.

The Democratic Alliance accused Mbeki of scoring an "own goal" against the government, the country, and investor and taxpayer confidence, while Bantu Holomisa's United Democratic Movement reiterated a call that parliament instruct Mbeki to institute an independent judicial commission of inquiry into the matter.

Mbeki's top aide, Frank Chikane, said the Constitutional Court had declared the Heath unit unconstitutional in November as it was headed by a judge, and gave the government one year to replace Heath.

"In the meantime, and in deference to the Constitutional Court ruling, the president will not be referring new matters to the SIU," Chikane said.

Allegations of bribery and corruption have surrounded the deal, and a preliminary study by the auditor-general last year called for a forensic audit after finding serious procedural flaws.

The auditor-general, the public protector and the Office for Serious Economic Offences have begun investigations into the deal in a probe co-ordinated by parliament's public accounts committee.

Initial areas of focus will be on subcontractors, possible exercise by individuals of undue influence on the contract process, and the failure of the government to reveal the true cost of the deal at the time.

Heath, who has won a reputation for unflinching probes into allegations of corruption but whose flamboyant style has caused several clashes with the government, has been openly supported by all members of the ANC-dominated public accounts committee.

Chikane stressed that the exclusion of Heath's unit from the probe should not be interpreted as the government going soft on corruption or having anything to hide.

With acknowledgement to Claudia Mpeta and Independent Online.