Claudia Lawrence's disappearance is being treated as suspected murder
The man behind the press campaign to find missing chef Claudia Lawrence has called for an independent inquiry into how the case has been investigated.
Martin Dales, a friend of the chef's father, Peter, said the police had devoted huge resources to the inquiry, but were no closer to finding her.
Miss Lawrence was last seen leaving her workplace in York on 18 March 2009.
North Yorkshire Police said it was "disappointed" by Mr Dales' comments which were not Mr Lawrence's views.
Ch Supt Iain Spittal, chief of staff for North Yorkshire Police, said: "Mr Lawrence has recently been personally briefed by the senior investigating officer and expressed his satisfaction over the conduct and progress of the investigation.
"The investigation has been, and continues to be, a thorough, professional but challenging inquiry."
He said the force had asked the National Policing Improvement Agency (NIPA) for a second review of the case.
Mr Dales, who runs the Find Claudia website, said while this was welcomed, the NIPA reports were only made public with the authorisation of the chief constable, and further transparency was needed.
"What is really needed now is an urgent independent inquiry with a public report," he said.
"Nothing less will do and transparency is vital if trust is to be restored in North Yorkshire Police."
North Yorkshire Police said a NIPA review of the case in May 2009 described the inquiry as "very comprehensive and effective".
Ch Supt Spittal said: "Many calls have been made to the incident room over the course of the past year and thousands of lines of inquiry developed.
"Due to the volume, it is not always possible to provide feedback on every call."
The disappearance of Miss Lawrence, who was 35 years old when she went missing, is being treated as suspected murder.
The investigation is one of the largest ever carried out by North Yorkshire Police and has so far cost more than £600,000.