Kate McCann, the mother of missing Madeleine McCann, has admitted for the first time that she may never find her daughter. In an interview with the Sun, she said she and her husband Gerry may have to effectively end the search next year because they are running out of money.

Madeleine, who was then three years old, disappeared in 2007 from the family's holiday flat in the resort of Praia Da Luz on the Portuguese Algarve.

Her parents believe she was abducted and have used money donated by the public to employ private investigators ever since the Portuguese police search was called off.

Kate McCann said: "There is only enough money in the Find Madeleine Fund to keep the hunt going until spring 2011.

"When the money runs out we will not be able to pay the investigators helping us to find Madeleine. It will be just me and Gerry left looking for her."

The McCanns say the search fund has dwindled to £300,000 from a peak of £2m. They have sent out "begging letters" to celebrities, including JK Rowling and Richard Branson, who they hope will provide funds for the private investigation to continue.

They hope the British public will also start donating again when they hear of their plight.

The McCanns are also hoping to persuade the British and Portuguese governments to conduct a review into the evidence surrounding Madeleine's disappearance.

In an open letter marking the launch of an online petition, the McCanns say: "We have tried in vain to get the authorities to play their part but our requests have seemingly fallen on deaf ears. It is simply not acceptable that they have, to all intents and purposes, given up on Madeleine. We need the authorities to do more.