Gerry and Kate McCann's anguish deepened tonight as police followed an anonymous tip off which claimed that their daughter's body was buried in
 scrubland nine miles from where she was abducted.

Mr and Mrs McCann, who are clinging to the hope that Madeleine is still alive, were with detectives when they were passed an anonymous handwritten letter and map.

It claimed the four-year-old was buried in scrubland, "under branches and rocks", seven metres from a road.

The map pinpointed a dirt track in an area near Odiaxere, north east of Praia da Luz, where Madeleine was kidnapped from her bedroom 41 days ago.

The letter was sent to Dutch newspaper De Telegraaf and passed on to the Portuguese police today.

Police said they are trying to verify the claim, but have yet to start searching the area, amid concerns the co-ordinates are not detailed enough.

A source close to the family said they were with Portuguese detectives when news of the letter came through.

"They found the whole thing very upsetting," the source said. "There was talk of a body and Kate was particularly distressed. It is being taken as seriously as any other line of inquiry."

It is believed the tip off may have come from the same anonymous source who predicted where the bodies of two murdered children would be found in Belgium last year.

The handwriting on the letter is said to be similar to that on a map received by the same newspaper, De Telegraaf, in June 2006, which correctly predicted the shallow graves of Belgian girls Nathalie Mahy, 10, and Stacey Lemmens, seven, who had disappeared while playing in front of a cafe in Liege.

A Moroccan man is awaiting trial for the murder but the anonymous source was never traced by police. De Telegraaf said the new handwritten letter was two paragraphs in length and written in Dutch.

The source said: "We received an anonymous letter with a map in it marked with the spots where Madeleine was buried.

"The police in Holland are taking it very seriously because it looks like the same sender as one we received one year ago in another case of missing children.

"The letter said the girl should be found six to seven metres from a road. We have been there but haven't seen anything but the area is so wide that you should be there with 100 searchers."

Both letters used the same phrases such as "the presumable hiding place", the handwriting was similar and both were accompanied with an A4 map printed from the website www.routenet.nl.

Chief Inspector Olegario Sousa said the information was being investigated and "everything necessary" was being done to validate the allegation. He said: "We are checking the information like we check everything in this case for importance."

Asked if any search would involve digging, he said: "If the information gives us a precise location where we can look, we will do it."

Portuguese Police said they have kept hundreds of visions and tips from clairvoyants about Madeleine's whereabouts in a file three inches thick. They have followed each one in case they are from the abductor.

Philomena McCann, Madeleine's aunt, said that the potential lead is upsetting and said she may fly out from her home in Glasgow to be with the parents in the Algarve.

Police chiefs were meeting this evening to discuss the possibility of sending specialist sniffer dogs to the area from Lisbon.