A couple from Yongin, just south of Seoul, has been put under emergency arrest for allegedly having maltreated their live-in niece to death, police said Tuesday.

The man and his wife, both in their 40s, are accused of having beaten their 10-year-old niece with a plastic broom and other objects and repeatedly throwing her into their home bathtub until she stopped breathing Monday.

According to the Yongin Dongbu Police Station, the girl lost consciousness after being forcibly put in and out of bathtub several times Monday afternoon before being transported by paramedics to a hospital, where she was pronounced dead of secondary shock.

Her death was reported to police as a child abuse case after doctors found bruises all over her body. The couple reportedly told police that they had inflicted physical punishment and water torture-style acts on the girl as discipline for not being obedient and potty trained.

The girl was said to have lived with her mother's elder sister and her husband since late October or early November last year due to the mother's work life and other personal reasons.

The girl had reportedly lived with her birth parents in another area of Yongin and attended school normally before moving into her aunt's house, police said.

It is the second fatal child abuse case in two months to make headlines in South Korea. In January, an adoptive mother from Seoul was indicted on charges of child abuse resulting in the death of a 16-month-old baby girl, who was adopted in February last year and died in October of severe abdominal injuries and internal bleeding.

The Yongin police said they will conduct an autopsy to determine the exact cause of the girl's death and noted there is also a trace of her being tied to something in the arm area.

Police said they plan to request arrest warrants for the couple after conducting further investigations into the case. (Yonhap)