Foster's secret reason for early release

Conman Peter Foster is expected to find out this week whether he'll get out of jail early, but the reasons are unlikely to be revealed to the public.

Foster's lawyers persuaded a Federal Court judge on Tuesday to close a court hearing to the public and seal legal material relating to the conman's bid for early release, which is based on a "new factor".

Barrister Saul Holt QC told Justice John Logan the stakes were "simply too high" for the 53-year-old, who is serving an 18-month sentence in the Brisbane Correctional Centre over his last weight-loss scam.

Foster has six months left to serve.

Reference was made in court on Tuesday to a new factor in the conman's case.

Mr Holt said Foster's conduct in relation to this was "of a kind that is worthy of recognition", but should not be revealed.

"The reality for him is that the risk of any knowledge of these matters ... is likely to have profound consequences," Mr Holt said.

Foster was in October 2013 ordered to serve 18 months of a three-year prison sentence for breaching court orders that banned him from the weight-loss industry.

It was over his involvement in the $6 million SensaSlim oral diet spray scam.

The notorious conman went into hiding and made out he was in Fiji.

However he was tracked down a year ago disguised as a hippie and living near Byron Bay in northern NSW.

Mr Holt admitted to Justice Logan that Foster had been in Australia when he purported to be in Fiji.

But the lawyer couldn't confirm for the judge a media report that Foster once said Justice Logan could "stick his sentence up his jacksie".

Before he closed the court, the judge determined he did have the power to order an early release for Foster, but said there was no precedent for it in Australia.

He said it was "both desirable and necessary" that the issues were not canvassed in public.

A decision is expected on Friday.