Two politicians have testified at the Schabir Shaik trial that they hit brick walls in their attempts to have Judge Willem Heath and his special investigative unit look at the multibillion-rand arms deal.

Shaik faces two counts of corruption and one of fraud.

Independent Democrats leader Patricia de Lille told the Durban High Court on Tuesday that in 1999 she had received information about corruption in the deal. She wanted Heath to investigate, but President Thabo Mbeki would not sign a proclamation.

The former chairperson of parliament's Standing Committee on Public Accounts (Scopa), Gavin Woods, said that in late 2000 his committee had wanted the Heath Unit to investigate the deal with the Public Protector, the National Directorate of Public Prosecutions and the Auditor-General, but had to settle for a joint investigation by the other three.

The Heath Unit had the power to have corrupt contracts cancelled.

The state says the exclusion of the Heath Unit was suspicious, specifically as referred to in a letter written in January 2001 by Deputy President Jacob Zuma. Advocate Billy Downer SC said it was their case that this was done because there was an agreement that Zuma would be paid a bribe, facilitated by Shaik, to protect French arms company Thomson from investigation.

But Woods conceded in cross-examination by Shaik's counsel Francois van Zyl SC that several government ministers, including then justice minister Penuell Maduna, the public protector and the director of public prosecutions were in favour of excluding the Heath Unit from the investigation, and that Zuma was only expressing the government's view.

Woods said he still found Zuma's letter puzzling. In re-examination he added that the other government officials did not copy their opinions to the major contractors in the arms deal, specifically Thomson.

He told the court that Scopa started looking at the arms deal after it was reviewed by the auditor-general. Scopa concluded that it must be investigated further.

Like De Lille, Woods wrote a letter to the president, asking him to consider issuing a proclamation. But a new Constitutional Court ruling stated that it was unconstitutional for a judge to head a unit like the Heath Unit.

In January 2001, Woods received a letter signed by Zuma, in his capacity as head of government business, stating there was no need for the Heath Unit to investigate.

"I was fairly alarmed. To get a letter this strongly worded and hostile was intimidating. It was a letter I had to take very seriously. I found it strange that it was written by Zuma, because government took the decision about the arms deal before 1999.

"Those who took the decision were all still in cabinet. Zuma had not been involved in the arms deal," he said, adding that Zuma had previously indicated his support for an investigation.

Woods said it was possible the Zuma letter could have been written on behalf of the government, but there was reason to question this.

He said the investigation went ahead, but he "shared suspicions that it was limited and weakened".

Woods eventually resigned as chairperson of Scopa.

The trial continues.

With acknowledgements to Estelle Ellis and The Mercury.