Chinese authorities have said they are unable to act over the treatment of an eight-year-old girl who has been tied to a tree by her grandparents for nearly six years.

Zhao Ziyi, from Louyang village in the Henan Province, was first tethered with rope in 2010 after her grandparents claimed she started attacking people.

Her grandparents have said Zhao started acting strangely after a series of high fevers, according to the South China Morning Post.

Her grandfather told reporters:"She would attack other children and older people.

"She is dangerous to others, so we have to tied her up here."

Zhao, who it is claimed suffers from mental health problems, lives with her two healthy brother with her grandparents. Her father, who is disabled, works at a factory in another town.

Her mother is also disabled and is thought to live elsewhere.

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It is not known whether she attends school or is allowed inside the house to wash.