It now seems almost impossible for Deputy President Jacob Zuma to avoid giving evidence in the trial of Schabir Shaik.

A revolving credit agreement signed by Zuma was provisionally entered into evidence this week and the state says it will dispute that it is an authentic document.

The agreement, signed by Shaik and Zuma, is dated 1999 and, according to Shaik's counsel Francois van Zyl SC, filed at parliament in the confidential register of members' interests.

For the court to get access to the original document, Zuma will have to waive his parliamentary privilege.

This also comes as forensic auditor Johan van der Walt said an employee of Shaik's Nkobi Holdings told him that the payments by Shaik to Zuma continued when the Scorpions were already busy with their investigation.

Van der Walt said he did not confirm this.

In his plea explanation, Shaik said there was a revolving credit agreement between him and Zuma.

But in his report, Van der Walt did not treat the money given to Zuma as loans. He called it payments which would be in line with the state saying that the money was paid to Zuma as an advantage.

During Van der Walt's cross-examination it emerged that the revolving credit agreement was one of three acknowledgments of debt signed by Zuma. In two of them Shaik charged no interest. In the other he charged interest at prime rate plus 2%.

It further emerged that Zuma might have paid back more money to Shaik than the state has recognised.

The agreement itself is barely two pages long. On it Shaik's name is spelt wrongly.

According to Van Zyl, it had been renewed since lapsing in May but Shaik and Zuma had not got around to signing the new documents.

"I assume you will tell me what the outstanding balance and interest is," Van der Walt said to Van Zyl during cross-examination.

"Never assume anything in a court of law*," Van Zyl answered.

The trial continues this week.

With acknowledgements to Estelle Ellis and the Sunday Argus.

* Like whether a faxed copy, conjured up like a rabbit out of a hat, is indeed the genuine article.