Scotland Yard's review of the Madeleine McCann case is a "ludicrous" waste of money, a senior member of the its governing body has claimed.
Jenny Jones hit out at David Cameron's controversial decision to involve the Metropolitan Police and said the move would deny other victims of crime the chance of justice while using up valuable police resources.
The review has already sparked faced fierce criticism amid suggestion the intervention could undermine the independence of the force.
Ms Jones, a member of the Metropolitan Police Authority and the London Assembly, told The Mail on Sunday: "The police should not take this case up in this way.
"It is ludicrous. This could take years and will cost millions. It is very unusual for police to step in like this and it is not an appropriate use of police resources."
She said the MPA would now be asking tough questions of the move, adding: "The Government is closing down the Forensic Science Service because there are not enough funds. This is a crucial part of police work.
"Although it is tragic and I feel for the McCanns, how can the Prime Minister justify spending millions of pounds on one case?"
Her comments echo remarks made by fellow Metropolitan Police Authority member Lord Harris last week.
Writing on his blog, he said: "Whilst no one doubts the desirability of doing what can sensibly be done to find out what has happened to Madeleine McCann, I can imagine that the senior leadership of the Metropolitan Police are not exactly happy about this.
"It again embroils their officers in a high-profile investigation, where the chances of success are unclear, and which will divert limited investigative resources away from other matters."
However Madeleine's parents, Kate and Gerry McCann, have welcomed the move.
They have said Prime Minister David Cameron gave assurances that all funds for the case review would come from central Government and would not eat into the force's budget.
Madeleine went missing from her family's holiday flat in Praia da Luz in the Algarve on May 3 2007, shortly before her fourth birthday.
Portuguese police, helped by officers from Leicestershire Police, carried out a massive investigation into her disappearance but the official inquiry was formally shelved in July 2008.
Since then no police force has been actively looking for the missing child.
The review will be led Detective Chief Inspector Andy Redwood, from the Homicide and Serious Crime Command (HSCC).
He has previously conducted an investigation which snared murderer Miguel da Silva after a cold case review.
The killer, who went on the run for 15 years after strangling mother-of-two Susan Martin, 44, in 1994, was jailed for life at the Old Bailey last November and told he must serve at least 16 years behind bars.
Mr Redwood will report to Detective Chief Superintendent Hamish Campbell, HSCC operational command unit commander, and the senior officer in overall charge of the HSCC, Commander Simon Foy.