The Balen Report on the BBC's coverage of the Middle East may still come to light, according to the London solicitor who has fought for two years for it to be released under the Freedom of Information Act.
Commercial solicitor Steven Sugar said a High Court ruling in favour of the BBC on Friday was not a complete victory for the corporation and gave "ammunition" to those who felt it was unaccountable and incapable of reform.
"It is a technical win by the BBC which has the result desired by it of weighting the Act in its favour and against the citizen.
"I hope the Information Commissioner or the Department for Constitutional Affairs will take the point to the Court of Appeal."
The BBC has repeatedly refused Sugar's request for the report, citing a section of the FoI Act that exempts it from releasing information relating to information held for the "purposes of journalism".
The case went to the Information Commissioner, who ruled in favour of disclosure, but that decision was last week overturned when the judge decided the tribunal had no jurisdiction to rule in FoI cases relating to public broadcasters.
Sugar said: "This matter is not over. The Information Commissioner may change his view given the new information he has obtained as a result of the tribunal case.
"Perhaps the new BBC Trust, under its new chairman, Sir Michael Lyons, will take a different view to BBC management and conclude that it is in the public interest for Mr Balen's report to be published.
"That would be consistent with the BBC Trust creating a new, more open and accountable relationship between the BBC and the public which pays for it."
Sugar has released a letter he has sent to Lyons, urging him to intervene to make the report public.
It said: "In this whole process, the BBC is giving much ammunition to those who take the view that it is an arrogant and unaccountable bureaucracy incapable of reform."