A parliamentary code of conduct former African National Congress chief whip Tony Yengeni stands accused of violating appears never to have been formally adopted, the special commercial crimes court in Pretoria heard on Tuesday.

Hilton Epstein, for Yengeni, told the court he could find no documentary evidence that the code, which governed members' interests, was adopted after being discussed in the National Assembly and the former Senate in August 1996.

Yengeni faces a charge of defrauding parliament as an alternative charge to the main charge of corruption. Epstein argued the alternative charge should be scrapped.

Yengeni also objected to the main charge, saying the state had failed to prove he had committed or omitted any act using his parliamentary powers in order to receive any benefit.

The charge sheet did not contain sufficient particulars to sustain a corruption charge or a conviction, Epstein charged.

He said the State had conceded Yengeni would not have been able to influence the arms acquisition process and could not prove that he tried.

His co-accused, businessman Michael Woerfel, was also expected to challenge the charges.

The charges against the men relate to an alleged 47% discount given to Yengeni when he bought a luxury Mercedes Benz 4x4 in a deal apparently organised by Woerfel - then managing director of European Aeronautic Defence Systems (EADS).

The State alleged that Woerfel sold the car to Yengeni for R182 563, just half the retail price of R349 950. Yengeni sold the Mercedes for R220 000 in November last year.

The State further alleged Yengeni received the vehicle with the intention to "use his power or exercise his influence to influence the arms acquisitions process" in favour of EADS predecessor Daimler-Benz Aerospace AG or DaimlerChrysler Aerospace AG.

Yengeni was chairman of parliament's joint standing committee on defence at the time.

EADS, a joint venture between DaimlerChrysler Aerospace and two European companies, has a 33% stake in Reutech Radar Systems, a Stellenbosch-based company that secured a R220-million contract to provide radar technology for four corvettes that form part of the country's multi-billion rand arms acquisition programme.

The forgery charge pertains to an agreement of sale drafted in respect of the Mercedes transaction.

Yengeni also faced a statutory perjury charge for allegedly giving false evidence to arms deal investigators, but this charge was withdrawn.

With acknowledgements to Sapa and Cape Argus.