National Assembly Speaker Frene Ginwala says that at this stage there is no evidence of misconduct against any current or former MP relating to South Africa's controversial R43 billion arms deal.

Addressing Parliament's watchdog public accounts committee today, she said documents referred to her by the committee did not substantiate allegations against MPs, including claims of kickbacks.

The documents have referred to current and previous members, including ANC Chief Whip Tony Yengeni - who is an ex-chair of Parliament's joint committee on defence - and former Defence Minister Joe Modise.

Both men have emphatically denied the allegations, and have threatened legal action to clear their name.

"I have studied these (documents) and agree that the allegations are not substantiated," Ginwala said. "Accordingly, I did not consider that there was a basis for referral to the disciplinary committee, nor to an ad hoc committee of the House."

If evidence did arise on the conduct of members surrounding the arms deal, she would act on it immediately, she said. Ginwala also rejected media reports that she had interfered in the arms probe - recommended by the committee and endorsed by National Assembly.

The investigation into the arms acquisition programme was crucial to Parliament's future, and should continue, she said. "The way we deal with it is going to have a very big impact on Parliament."

Meanwhile, Institute for Democracy in South Africa political analyst Richard Calland said the committee was being undermined by the huge turnover of ANC and opposition MPs serving on it.

The multi-party committee's work to oversee public expenditure was now being threatened, he said. "It remains to be seen whether the committee can re-establish itself with new people."

Calland was reacting to today's announcement by Yengeni that the ANC would "strengthen" its representation on the committee "because it has important matters to consider".

He described the changes as a "palace revolution", and said it would have implications not only for the R43 billion arms investigation, but the committee's future work. "It undermines a very stable committee."

Yengeni has appointed his deputy Geoff Doidge as chair of the ANC's study group on public accounts.He will also become the party's official spokesman on public accounts, effectively demoting ANC MP Andrew Feinstein, who held both positions.

Feinstein remains a committee member, with Doidge joining the committee as a replacement for Serake Leeuw, who is now Welkom's mayor. However, Feinstein said he was saddened by the move and said he would reconsider his position on Scopa and Parliament. Feinstein is widely regarded as one of the ANC's most vocal, hard-working and talented MPs.

Along with committee chair Dr Gavin Woods (IFP), Feinstein led the charge to ensure the executive was accountable to Parliament, including on the matter of the arms deal.

Feinstein incurred the wrath of Minister in the Presidency Essop Pahad last year for his views on the arms deal, but was reportedly defended by Deputy President Jacob Zuma.

Feinstein appears to have become the latest casualty of the fallout over whether the Heath Investigating Unit should be included in the multi-agency probe.

With acknowledgement to Sapa and SABC News.