Proof? ... Peter Foster reading Fijian newspaper The Sunday Times.

Peter Foster claimed in October to be living in Fiji.

On-the-run conman Peter Foster has again been found in contempt of court over his slimming spray scam, SensaSlim.

Foster went on the run in late October, breaching his bail by failing to turn up to court in Brisbane where he was sentenced to at least 18 months' jail on an earlier contempt of court charge.

The serial conman's wherabouts are unknown, although in late October he told Fairfax Media he was in Fiji.

Federal Police have issued an Interpol red notice asking international police forces to arrest Foster, 51.

On Tuesday, Federal Court judge John Dowsett found Foster in contempt over his failure to appear in court in Brisbane on September 27.

Justice Dowsett said he would also dismiss Foster's attempt to appeal his jail sentence unless he gives himself up to police before 4pm next Tuesday.

''Taking the most favourable view of Mr Foster's conduct, that he had genuine doubt about the legal correctness and propriety of the course which I foreshadowed, he must now submit to the jurisdiction of the Court,'' Justice Dowsett said.

''Taking that most favourable view of his conduct, I shall allow him one last chance to comply with the order of 26 September 2013.

''I do not know his present location.  I shall allow him seven days in which to surrender himself. If he does not do so, the appeal, without further order, will stand dismissed for want of prosecution.''

The Australian Competition and Consumer Commission pressed for contempt charges against Foster after it emerged that he was behind bogus slimming product SensaSlim, in defiance of a 2005 Federal Court order banning him from the weight-loss industry.

Foster has a long history of slimming scams, stretching back to the 1980s when he sold tea he claimed caused weight loss.