Kate and Gerry McCann have dismissed fierce criticism of Scotland Yard’s intervention in the search for their missing daughter Madeleine.
They 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.
In their first reaction to the development, they said they would like to thank the Conservative leader for his intervention.
Mr McCann said it would go a long way to addressing one of their key complaints about the inaction on the part of UK police.
“We welcome their involvement,” he said.
“We have been calling for a transparent, independent review. We have yet to see exactly the details of their involvement and what it will entail and I hope this does improve communication between the Home Office and ourselves, which obviously we have complained about, including yesterday.”
Speaking in Dublin, he added: “I’m sure it will go a long way to (addressing) one of our key disgruntlements, which was that British police had lots and lots of information and it was just sitting there and no one was looking at it.
“The Met has excellent expertise in reviewing major crimes, so we are very pleased and we would like to thank David Cameron for his intervention.”
Mrs McCann said the announcement from Mr Cameron came out of the blue as they travelled to Ireland to promote her book.
“I think we were a bit surprised because we weren’t expecting to hear anything, if we did, until next week,” she said.
“It all seemed to happen very suddenly.”
She added: “But nothing is going to happen overnight from now on.”
Mr McCann said they would have to wait and see the outcome of the review.
“How this pans out over the coming weeks and months will really be the acid test,” he said.
Meanwhile, however, Metropolitan Police Authority member Lord Harris said the intervention undermined the independence of the force and the investigation would use up valuable resources.
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.”
Lord Harris added: “This is in response to an open letter in The Sun and is entirely predictable in terms of the ‘pulling power’ of News International on Government policy.