A Vietnamese man has claimed he is the real father of a woman whose plight gripped Cambodia after she apparently spent 18 years living in the jungle, her adoptive family said Monday.

The paternity claim, which the woman's adoptive family now believe is genuine, adds a new twist to a saga which began in 2007 when a naked and filthy woman was discovered trying to steal food from a farmer.

The woman -- soon dubbed "jungle woman" by Cambodians -- was found hunched over like a monkey, scavenging on the ground for pieces of dried rice.

She was taken in by a Cambodian family who identified her as Rochom P'ngieng, a girl who went missing in 1989 while herding water buffalo in Ratanakiri province, around 600 kilometres (400 miles) northeast of Phnom Penh and home to some of the country's wildest jungle.

Now a 70-year-old Vietnamese man, named Peo, claims the woman is in fact his daughter who went missing in 2006 and has a history of mental health issues.

Rochom Khamphy, a member of the adoptive family, said Peo recognised her after seeing recent photos on Facebook.

"He claimed she is his long-lost daughter," he told AFP by telephone. "He recognises her by a spot on her lip, ear conditions and a scar on her left wrist."

The Vietnamese man has since made two visits, the latest on Saturday, and has agreed to pay the woman's adoptive family $1,500 for taking care of her.

Khamphy said his family were inclined to believe the man is her father and were awaiting approval from the Cambodian authorities to give her back.

"If she was not his daughter, he would not want her back because she is mentally ill. He said he feels pity for her, that is why he wants her back," he said.

In a letter given to her Cambodian adopted family and seen by AFP on Monday, Peo said his daughter was called Tak.

"Recently some young villagers suddenly found her information and pictures online. They showed me and I discovered she is now in Cambodia, raised by Cambodians," Peo said.

Chhay Thi, provincial coordinator for local rights group ADHOC, told AFP he was monitoring the transfer process for any signs of human trafficking, but added he was inclined to believe Peo.

"Their faces are similar. If she is not his daughter, he would not take her back because she is mentally-ill," he said.