The body of missing German tourist Monika Billen has been found under a tree 2.9 kilometres west of Emily Gap, a popular tourist site outside Alice Springs in Central Australia.

Key points: Monika Billen's body was found under a tree near Emily Gap

Monika Billen's body was found under a tree near Emily Gap Police had resumed the search for the missing tourist after receiving extra information from her phone companies

Police had resumed the search for the missing tourist after receiving extra information from her phone companies Her family in Germany have been contacted

Although police had called off the search for Ms Billen, who had not been seen since New Year's Day, they continued looking for her after receiving extra information from her phone companies.

They found her body at 3:15pm.

"Police received additional information from Ms Billen's telecommunications provider and have continued with aerial searches in specific areas for the past two days," Superintendent Pauline Vicary said.

"It has required extensive work, interpreting data from both international and national phone providers, but the outcome assisted in narrowing down the search parameters and eventually locating Ms Billen."

Police contacted the family — who sent a heartbreaking letter to the ABC on Tuesday — to advise them of the outcome.

A report will now be prepared for the coroner.

While Superintendent Vicary said it was upsetting news to break, it was a relief to finally provide some answers.

"Members have worked tirelessly to locate the 62-year-old since she was reported missing to police on January 11," she said.

"It is deeply upsetting that we have to tell her family this sad news, but we are relieved to be able to provide them with answers."

She thanked all police, NT Emergency Services, Parks and Wildlife and council rangers personnel who had been involved in the search.

Monika Billen was last seen in Alice Springs on New Year's Day. ( Submitted: Billen family )

Search efforts had focused on Emily Gap

Ms Billen, 62, had been travelling Australia alone and was last seen by staff at the Desert Palms Resort in Alice Springs, where she had been staying for more than a week.

Yet it took more than week for a search to begin, with the resort staff waiting three days after she failed to check out on January 5 to report her disappearance to police.

Police found she had also missed a scheduled flight to Darwin on January 5.

Emily Gap, near where Ms Billen's body was found, had been a focus of search efforts, after a member of the public reported seeing her there.

Police had also found brochures for local walks during a search of her room, leading them to believe she had gone hiking.

In her last email to her family on December 31, Ms Billen detailed her plans to walk the region.

"In the heat I take more or less extensive walks in the surroundings of Alice Springs in Central Australia," Ms Billen wrote to her family.

"Somehow the heat fits well with the landscape … I took a picture from the [Olive Pink] Botanical Garden lookout hill, which is near my accommodations (sic) and offers plenty of shady places to sit, dream and read."

Map Monika Billen's body was found under a tree near Emily Gap.

Experienced traveller

Earlier this week, Ms Billen's family in Cologne, Germany, wrote a letter imploring the Alice Springs public to come forward with any information which could lead to her discovery.

They said she was an experienced traveller, and had feared she had been in an accident or the victim of a crime.

"Monika has travelled off the beaten path for many years and in many countries and has always proceeded with caution," they wrote.

"It is normal for her to take several days between messages to us, and that is why we did not know at first that she was missing.

"We have been consumed with worry ever since we heard of Monika's disappearance, especially because we know her as a very responsible and capable person."

They also took the time to thanks the NT Police "and those who have been helping them search for Monika".