The Scorpions fired the first salvo in their battle for independence this week as President Thabo Mbeki appointed Judge Sisi Khampepe to investigate whether the unit should be brought under police control.

New Scorpions chief Vusi Pikoli, who succeeded Bulelani Ngcuka as National Director of Public Prosecutions last month, and his deputy, Leonard McCarthy, gave MPs a rapid-fire presentation on the successes of the 519-member team on Thursday.

McCarthy dismissed reports of tensions between the Scorpions and the police, saying: "It's a red herring. Our people work with the police every day. We co-operate at top level and we support what they do."

Reporting that they had exceeded many of their targets, Pikoli and McCarthy denied that the unit picked only winnable cases and said it tackled tough jobs no one else wanted

Mbeki this week gave Khampepe, a former Truth Commission member and one-time Deputy Director of Public Prosecutions, four months to investigate "options regarding the appropriate location of the directorate".

Cabinet spokesman Joel Netshitenzhe said Mbeki would spell out the terms of reference of the one-person commission later, but said they would include the rationale behind the unit's creation in 1999, its relationship with other security agencies and the best way to strengthen its fight against organised crime.

The ANC is split over whether to rein in the unit, which has a conviction rate of over 80% and is responsible for many of the most significant crime busts in the country.

Political insiders have told the Sunday Times that Mbeki wants to protect the unit's functional independence while allies of Deputy President Jacob Zuma, the most famous target of a Scorpions investigation, want the unit brought to heel.

In a private meeting with party whips earlier this year, Zuma said MPs should put pressure on the Scorpions and should summon them to Parliament every day if necessary.

Pikoli avoided any direct appeal for continued independence when he led two days of testimony by his team before Parliament's portfolio committee on justice.

Instead, he managed a powerful presentation of the work of his National Directorate of Public Prosecutions and its Scorpions and Asset Forfeiture sub-units.

Pikoli and McCarthy faced sometimes hostile questioning from MPs, including a blunt reprimand by Luwellyn Landers, chairman of Parliament's ethics committee.

Landers complained that a Scorpions investigator on the team probing the R17-million travel voucher fraud by MPs and their travel agents had made an unannounced visit to a Parliamentary official with a subpoena for a confidential register of members' assets.

Landers said the agent was lucky he had been away because "I would have told him to take his subpoena and shove it I won't say where".

Pikoli declined to discuss the options facing the Scorpions, telling the Sunday Times he would make a direct presentation to Khampepe once the commission got under way.

But he said moving his unit to the police would not resolve the financial pressures he highlighted during his presentation to MPs.

He promised that the Scorpions would be more proactive in future, would mount public-interest operations to prevent crime and would contribute through their work to economic growth and job creation.

With acknowledgements to Brendan Boyle and the Sunday Times.