South Africa's highest court has cleared the way for prosecutors to apply for the extradition of Brett Kebble murder suspect John Stratton.

But the National Prosecuting Authority has shied away from publicly confirming when and if it will launch extradition proceedings against the elderly Australian.

The Constitutional Court's 11 judges yesterday unanimously dismissed Stratton's bid to challenge the South Africa-Australia extradition agreement, finding it had "no prospects of success".

The decision means that the NPA faces no potential legal obstacles in applying for Stratton to be extradited from Australia to face trial in South Africa, along with convicted drug smuggler Glenn Agliotti, for the mining magnate's killing.

Agliotti is scheduled to go on trial for Kebble's killing, which the state is prosecuting as an "assisted suicide", in July.

Speaking yesterday, Stratton's attorney Rael Gootkin said 74-year-old cancer patient Stratton, who Kebble's father Roger and brother Guy have described as a "cockroach", would challenge any attempt by the NPA to extradite him.

"To the extent that the state still intends seeking our client's extradition from Australia, the challenge to the extradition will now move to Australia, where our client will take up his continued challenge to oppose the extradition that may be sought by the National Prosecuting Authority," he said.

NPA spokesman Tlali Tlali said yesterday the state had not yet seen the Constitutional Court's order on the Stratton application and would consider commenting "only once we have examined the order and established the implications it has for us".

In papers before the Pretoria High Court, Scorpions investigator Andrew Leask stressed that the state wanted Stratton in the dock with Agliotti when the Kebble trial begins.

"Because the state's case is founded on the allegation of a conspiracy between (at least) Mr Agliotti and Mr Stratton, it is of utmost importance that Mr Agliotti and Mr Stratton should be tried together. Separate trials are highly undesirable and prejudicial to accused persons, witnesses and the prosecution," he said.

With acknowledgements to Karyn Maughan and The Star.