Parents of Polish girl claiming to be Madeleine McCann say they're 'devastated' by daughter's claims

The parents of a girl who says she is missing girl Madeleine McCann have released a statement rejecting their daughter's claims.

According to 7NEWS Australia, Julia Faustyna's parents released the statement through a Polish missing persons website, saying the reason for their daughter's claims is due to issues with her mental health and a desire to be popular.

The 21-year-old recently became headline news after claiming she could be Madeleine McCann - the girl who disappeared during a family holiday in Portugal in 2007.

Faustyna, who has also gone by several other last names including Wendell and Wandelt, created an Instagram account with the username @iammadeleinemccan, where she has posted several photos comparing herself to McCann.

The 21-year-old from Poland pleaded with authorities, the McCann parents and her own parents to get DNA tests to try and prove she is the missing girl.

Faustyna has claimed in her Instagram bio that McCann's parents agreed to the DNA test but the parents have not announced this themselves.

Private investigator Dr Fia Johansson told 7NEWS Australia that she and Faustyna were going to court to seek a DNA test order.

Johansson told 7NEWS Australia Faustyna wasn't "doing this for publicity" because she also believed the theory she could be Madeleine McCann.

Faustyna's parents disagreed with the theory and said she has made it up because she wants to be in the public eye.

"We always tried to help her get back on her feet. Julia has been of age for several years. She has moved out of the house, [she] refuses treatment, [and] doesn't take medicines regularly," 7NEWS Australia reported her parents as saying.

The 21-year-old Polish girl claimed she has post-traumatic amnesia after being sexually abused by a paedophile who she recognised but could not identify from the Find Madeleine website.

Fautsyna also allegedly said her parents pulled her out of therapy when she began "asking questions" but her parents have denied these accusations.

"We always tried to understand all situations that happened with Julia. Numerous therapies, medicines, psychologists and psychiatrists. Julia had it all guaranteed. She wasn't left alone," 7NEWS Australia reported.

They said "it's obvious that Julia isn't Maddie" and they are "devastated" by the dilemma their daughter has put them in.

7 News Australia also reported Fautsyna's parents have also received threats from their own daughter.

"Threats to our address from Julia, her lies and manipulations, activity on the internet. We've seen it all and we've tried to prevent it, to explain, we've asked her to stop."

Fautsyna's parents said they won't be making any further comment on the situation.