AUSTRALIAN Federal Police withheld evidence that might have freed Dr Mohamed Haneef. Though they concede the material, if genuine, let Dr Haneef off the hook, it was never shown to the attorney-general, the Commonwealth Director of Public Prosecutions or the magistrate supervising the Gold Coast doctor's detention in the Brisbane watchhouse last year.

Dr Haneef was suspected of aiding a British terrorist cell by leaving an old SIM card with his cousin Dr Sabeel Ahmed in 2006. But on the face of it, the material Scotland Yard provided the AFP proved that Dr Ahmed was not a member of the cell that tried and failed in June last year to detonate car bombs in London and carrying out an attack on Glasgow airport.

In the midst of those events, Dr Ahmed's brother Kafeel left a message confessing that he was engaged on violent jihad: "This is the 'project' that I was working on for some time now … Every thing else was a lie! And I hope you can all forgive me for being such a good liar!! It was necessary."

Scotland Yard has not challenged the authenticity of that message. In April this year, Mr Justice David Calvert-Smith in the Old Bailey declared that there was "no sign" of Dr Ahmed "being an extremist or party to extremist views".

But senior AFP sources have told the Herald the Australian police believe it was concocted to provide cover for Dr Ahmed and others in the UK and elsewhere.

Dr Haneef's solicitor Rod Hodgson of Maurice Blackburn says the police view suggests bias. "A British court didn't take the view it was a sham and no other objective observer would take that view, so why would Australian police take that view unless they lacked balance and objectivity in their investigation?"

Police told the Herald they could not reveal the existence of the message to anyone at the time. It had been given to them on condition it was "closely held" because Dr Ahmed had not yet been told it was in the possession of police.

Mr Hodgson told the Herald the police should have "put its cards on the table". He argued police were aware of the jihad message which "calls into question the professionalism and objectivity of the person or people who made the decision to charge Dr Haneef".

Those charges were dropped after a fortnight. The jihad message was revealed publicly during the April proceedings against Dr Ahmed. As early as next week the Government will release the report of the retired NSW Supreme Court judge John Clarke into the Haneef case.