Police said Monday they have sought an arrest warrant for a man suspected of abusing his 2-year-old adopted daughter to the point she fell unconscious with bleeding in her brain.

The Gyeonggi Nambu Police Agency said the suspect, who is in his 30s, admitted to hitting the child with his hands on Saturday morning because she "kept whining."

According to the man, the girl then fell asleep, but when she didn't wake up several hours later, he took her to a hospital near his home in Hwaseong, about 40 kilometers south of Seoul.

Hospital workers determined she was in a serious state and sent her to a bigger hospital in Incheon, 40 km west of Seoul, where doctors discovered bleeding in her brain and bruises on her face and body, and reported the case to the police.

The girl underwent brain surgery but has yet to regain consciousness.

The suspect, who has been in police custody since Sunday, told police he previously hit the child last Tuesday and Thursday, four to five times on each occasion, using his hands and a wooden shoehorn.

Police said they are looking into the possibility she was abused prior to that, given that she was adopted by the suspect and his wife in August.

Hospital workers reportedly discovered bruises that appeared to be from different times on the girl's buttocks, chest and thighs.

No previous reports of child abuse involving the family have been filed.

The agency that gave her up for adoption said there were no signs of abuse when its workers visited the home in October, January and April.

The couple has four biological children, and none of them reported abuse during a preliminary investigation conducted by child services and the local government.

The father told police he and his wife adopted the 2-year-old from an orphanage where they were volunteering in 2019.

"We will continue to look into whether the adoptive father has an additional history of abuse and whether the adoptive mother took part in the abuse," a police official said.

Child abuse has received widespread national attention in recent months, after a 16-month-old girl, known as Jung-in, died last October from severe injuries sustained in the hands of her adoptive parents.

Prosecutors have demanded the death penalty for the adoptive mother and 7 1/2 years in prison for her husband.

The couple's sentencing hearing is scheduled for Friday. (Yonhap)