The Democratic Alliance Wednesday asked Parliament's public accounts committee, Scopa, to reopen the investigation into alleged irregularities in South Africa's weapons procurement deal.

"We think there is circumstantial evidence that the truth is not being told," said MP Helen Zille at a press conference at Parliament.

She said it is the duty of opposition parties and media to dig into the matter and uncover the truth.

The party's public accounts spokesman, Eddie Trent, said a number of pieces of evidence have come to light that support allegations that material changes were made to the joint investigation team's (JIT) report outlining certain irregularities in the multi-billion-rand arms deal.

"It is now common knowledge that the draft JIT report was subject to substantial changes which were designed to remove a number of embarrassing revelations regarding irregularities in the acquisition process of the arms deal," he said.

Trent said he has written to Scopa's chairman, Francois Beukman, requesting him to place the matter on Scopa's agenda when Parliament reconvened next week.

He said Beukman has agreed to a debate on whether the matter should be re-opened.

Trent said Scopa should investigate fully evidence that the JIT report was changed to reflect that "government's contracting position was not flawed".

He said the exclusion of much of former secretary of defence Lieutenant-General Pierre Steyn's criticism in the report should also be investigated.

Steyn was alleged to have been appalled by the investigation that he said was "designed to give legitimacy to political manipulation".

He allegedly argued that the procurement process was "riddled with large-scale irregularities".

"These allegations have re-ignited the controversy surrounding the arms deal and have raised even more questions about the conduct of the executive as well as the Auditor-General," said Trent.

He said the situation is untenable.

"For as long as questions of this nature continue to linger, the reputation of parliament and of the executive, and indeed the credibility of the Attorney-General will continue to be undermined," he said.

Durban businessman Schabir Shaik is currently standing trial in the Durban High Court on fraud and corruption charges linked to the arms deal.

With ackowledgements to Sapa and The Natal Witness.