Hunt for Madeleine McCann needs more cash to continue

Scotland Yard is to ask for more money to continue its six-year investigation into the disappearance of Madeleine McCann.

Detectives are struggling to resolve a final lead, which, if it fizzled out, could have brought the £11m Government-funded investigation to an end next month.

I understand that the Home Office is willing to carry on paying for the last bit of work to be completed.

A source said: "We will be asking for more money because we need to complete the work we are doing. It is complicated and not as straightforward as we had hoped, but it is worth doing."

Madeleine was nearly four years old when she vanished without trace from her family's rented holiday apartment in Praia da Luz, Portugal, in May 2007.

The Portuguese police closed their investigation 15 months later, after finding nothing to explain her disappearance.

In 2011, after an appeal from her parents Kate and Gerry McCann, the then Prime Minister David Cameron asked Scotland Yard to investigate with special Home Office funding.

Sixteen months ago then Scotland Yard Commissioner Sir Bernard Hogan-Howe said his squad - reduced in 2015 from 30 to three staff - was expecting to close a final investigative lead within months.

"That line of inquiry probably at the moment is the conclusion of this inquiry," he said.

In April this year, Assistant Commissioner Mark Rowley said detectives were still following a critical lead.

"We have a significant line of inquiry which is worth pursuing and because it's worth pursuing it could provide an answer - but until we've gone through it I won't know whether we are going to get there or not."

Police will give no details of the lead - nor why it is proving so difficult to resolve. But they want more time to pursue it.

There has been speculation that it involves a hunt for a suspect or a key witness, but none of that has been confirmed.

Retired Metropolitan Police detective Peter Kirkham said: "Media interest and the political drive for it to be done in the first place will add to a reluctance to stop the investigation until they are absolutely sure they have done everything they can.

"If a line of inquiry has any signs of life in it whatsoever, they will be saying 'this is here and we can do it but we'll need this amount to do it and if you don't wish to pay for it that is your decision'."

A spokesman for Madeleine's family told Sky News: "The McCanns will be pleased. The fact that the police feel there is still work to be done which needs funding is very encouraging.

"They remain grateful to all the officers involved in the investigation."

Scotland Yard said: "Funding is in place until the end of September. Any details about future funding will be released when appropriate."

The Home Office confirmed that funding for Operation Grange had been provided until the end of next month.

"The level of funding provided is a reflection of the wide-ranging and complex nature of the investigation which the police have deemed necessary to undertake," a spokesperson said.

They added that they have not received a new funding request from Scotland Yard but that "any future request will be considered carefully".