Former All Blacks rugby great Jonah Lomu can run again but any return to first class rugby is still a "wee while" away yet, he says.

Seven weeks after undergoing a lifesaving kidney transplant, Lomu said he promoted himself from walking to running over the weekend and completed a 25 minute jog at three-quarter pace.

He believed the exercise capability of his body was not far from reaching the same level as when his kidney disease was in remission in the late 1990s, up until when he was forced to give rugby away as his health failed in 2002.

"I'm pretty close. I'm at about 85 per cent in terms of training," Lomu told the New Zealand Holmes television show.

"The only thing that's missing is full-blown weights but that's good."

Lomu, 29, has been given a fighting chance by doctors who placed his new kidney in the less vulnerable position behind the ribcage rather than in the lower abdomen.

A weekend newspaper report that he was targeting next year's sevens World Cup was inaccurate, he said.

It was hard to tell when he could be back in action but he remained positive that he could defy most conventional medical thinking and return to top level rugby with a new kidney.

"I'm a wee while away but the body's a funny thing," he said.

"Things are coming along quickly. Every day I'm seeing different improvements in myself.

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