Johannesburg - Cape Town mayor Patricia de Lille is expected to testify at the Seriti Commission of Inquiry on Thursday.
She was the initial whistle-blower regarding the arms deal and called for Parliament to investigate it.
At the time, she was a Pan Africanist Congress MP.
The commission, which is chaired by Judge Willie Seriti, was appointed by President Jacob Zuma three years ago to investigate alleged corruption in the country's multi-billion-rand arms procurement deal in 1999.
On Monday, losing bidder Richard Young was expected to give evidence at the inquiry, but failed to attend.
In letters read out by his attorneys, Young said he recently had a corneal transplant which affected his vision, meaning he would only be able to testify for an hour or two each day.
Three days had been set aside for his evidence.
However, Young said he would need a week or two, without cross-examination, to give his evidence-in-chief. - Sapa