Emotional: Nahua (red coat), Mr Mu (left) and adoptive father (right) in the emotional exchange on Feb. 2  CEN

After adopting a young girl years ago, a couple from north-west China’s Urumqi city had to do the unimaginable when they discovered she was a child trafficking victim.

They gave their adopted daughter back to her biological parents on February 2 after finding out they had been searching for her for a number of years, reports Huanqiu.com, an affiliation of thePeople’s Daily Online.

The father saw a ‘kid wanted’ advertised on a public account on China’s Twitter-like WeChat social media platform, when they realized it was their daughter they phoned the police.

After they informed the police of their shocking discovery, they decided in the end to let the girl – who goes by the false name ‘Nahua’ – go back to her biological family.

In 2010, Nahua was reportedly kidnapped while she was playing outside her home by a human trafficking ring in China’s north-western Xinjiang Uygur Autonomous Region.

At the time, her biological father, surnamed Mu, was a migrant worker, working as an electrician. His wife and daughter who then was two-years-old would travel to the city and come and stay with him.

Mr Mu recalled that he let Nahua out of his sight for no more than two minutes before she was taken.

After her apparent kidnapping, he desperately searched up and down the country for Nahua, and even had a fierce falling-out with his wife which led to their divorce just one year after the tragic incident.

Mr Mu even sold his house in order to fund his travel throughout Xinjiang to find Nahua. He also gave up his job which paid 5,000 Yuan (£522) a month.

But Mu did not give up the search, and went from police station to police station in every city he could afford to visit over the past six years.

According to the report, whilst Mr Mu was searching high and low for his daughter, she had been sold for 5,000 Yuan – the same price as a month’s work for Mr Mu – to a couple in Xinjiang’s Toksun County, north-west China.

At the beginning of this year Mr Mu finally made some unexpected headway in his search for his daughter with the help of social media.

He posted an online plea directed at the local authorities and internet users in general, to help him look for his daughter.

In the post he included a picture, also noting that she had a very specific and easy-to-spot mole growing under one of her arms.