The girl has caught the attention of the authorities because of her politeness and her lack of Italian.

Internet campaigners think the girl could be one of several missing people, including Madeleine McCann who disappeared in 2007, and think she bears a striking resemblance to her.

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The teenager has been walking around with old clothes on, no belongings and has not accepted cash from locals.

Maddie and possible Maddie

Could this homeless girl really be Maddie? (Image: Missing Persons of America*GETTY)

Homeless girl

Locals have given the girl the name ‘Maria’ (Image: Missing Persons of America )

There have been several people that think it may be Madeleine McCann who would be 13 now

Missing Persons of America

Photos have been shared of the teenager online in a hope that she can be reunited with her family for Christmas.

Madeleine vanished from Praia da Luz holiday resort in Portugal in May 2007 at the age of three and authorities are still trying to understand what happened to her.

The Italian police have tried to identify the girl, who is sleeping rough on the streets with no passport or ID.

Madeline's parents

Madeleine’s parents are desperately trying to find their daughter (Image: GETTY)

Locals think she is called Maria as that is the name she responds to.

Critics think this girl is not Madeleine, who would be 13 now, as she does not have the blemish on her eye.

The website, Missing Persons of America wrote on a page for this girl, said: “There have been several people that think it may be Madeleine McCann who would be 13 now.

Missing person America

The teenager has been walking around in tattered clothing (Image: Missing Persons of America )

“Madeleine had a distinctive mark on her eye and it would be easy to tell if it was her by that identification.”

Campaign group Houston’s Voice For The Missing wrote on Facebook: “This girl needs help. I have been in constant contact with everyone from NCMEC, Rome police, locals journalist, the embassy, locals and anyone else I could think of.

“Police refuse to identify her. I found a local willing to go out to her then call me on facetime so maybe I get get something out of her. But we will see.”

She has also been linked to a number of other missing persons cases, including Amanda Adlai, who was abducted in Michigan in 2008, and Maria-Brigitte Henselmann, who disappeared from Germany in 2008.