President Jacob Zuma has appointed Free State High Court President Hendrick Mmoli Thekiso Musi as a member of the Commission of Inquiry into the so-called arms deal.

Musi is replacing Justice Willem Jacobus van der Merwe, who indicated that he would no longer be able to serve as a member of the commission for personal reasons.

The commission was appointed by Zuma in October to look into allegations of fraud, corruption, impropriety or irregularity in the Strategic Defence Procurement Package, otherwise commonly known as the arms deal.

Headed by Supreme Court of Appeal Judge Willie Seriti, the commission is to investigate six areas, including whether any person or persons within and, or outside the government may have improperly influenced the awarding or conclusion of any of the contracts in the arms deal procurement process.

When announcing the commission, Zuma said it would complete its work within two years.

"We once again wish Mr Justice Seriti and his team well in the execution of this important task,” said Zuma in a statement.