Political parties have accused the government of exercising double standards in appointing a judicial commission of inquiry to probe allegations of apartheid-era spying against National Director of Public Prosecutions Bulelani Ngcuka.

Democratic Alliance justice spokesperson Sheila Camerer said, however, the commission was probably the government's best means of damage control for an important institution in the criminal justice system.

But, ironically, while President Thabo Mbeki was prepared to initiate an independent investigation into seemingly unfounded spy allegations, the findings of which would be largely inconsequential, he had made every effort to discourage independent investigation into the arms deal, the findings of which would have serious repercussions for South Africa.

"This is an unfortunate case of double standards," she said.

"Whether or not Ngcuka was an apartheid spy, while interesting, has absolutely no bearing on his ability to do his job now, or on the merits of the Scorpions' investigation into Deputy President Jacob Zuma's alleged role in possible corruption in the arms deal".

The only bearing the findings of the commission would have was on the "acrimonious infighting in the ruling party".

However, it would at least allow Ngcuka to clear his name and put the dirty business behind him, Camerer said.

African Christian Democratic Party leader Kenneth Meshoe agreed it was a case of double standards, considering the government's reluctance to investigate allegations of corruption against the deputy president.

"We find it strange that the government has acted so quickly in initiating this commission when there have been incidents in the past where they have been asked to establish enquiries and they have been reluctant to do so.

"The evidence against Deputy President Zuma reported in the media seems far more serious than that against Ncguka.

"One is inclined to think that this (commission of inquiry) is designed to draw attention away from the allegations against Deputy President Zuma and arms deal corruption," Meshoe said.

Justice Minister Penuell Maduna announced on Friday Mbeki had appointed former Supreme Court of Appeal president Judge Josephus Johannes Francois Hefer to chair the commission.

Hefer would be the only member of the commission, and report to Mbeki within a month, or as soon as possible thereafter, Maduna said. – Sapa.