A toddler who was viciously attacked in an elevator in Chongqing, allegedly by an 11-year-old neighbor, is in stable condition but will need surgery next week, his family said on Thursday.

Li Xinyuan, who is 18 months old, has been in intensive care at Chongqing Medical University Children's Hospital since Nov 25. The toddler has fractures to his skull and right eye socket, said his father, Li Shuyong.

"Doctors told me he was very weak," the father said. "I saw my son several days ago when he went through an X-ray exam."

Li Shuyong claims an 11-year-old girl, who lives in the residential building and does not know Li Xinyuan, attacked his son.

Changshou district police have refused to disclose information about the case because it is under investigation. Police have not named a suspect.

The elevator attack was captured on surveillance cameras. The footage shows the boy's grandmother leaving the elevator while pulling an empty stroller. As she leaves, a young girl with a backpack enters and can be seen picking Li Xinyuan up.

The elevator doors then close before the grandmother can collect the toddler.

"I pressed the button to try to open the elevator and get my grandson, but it was too late," she told a Chongqing television station on Nov 27.

As the elevator ascends to the 25th floor, the girl appears to slam the child onto the floor before repeatedly slapping and kicking him. When the doors open, the girl is seen throwing the child out of the elevator.

The grandmother, surnamed Wu, said she arrived on the 25th floor and found the girl. The girl claimed the toddler had been taken away by another boy, but later said another girl had taken Li Xinyuan.

"She told me she couldn't see clearly whether it was a boy or a girl that took my grandson away," the grandmother said in the TV interview. "She even comforted me, telling me not to worry."

Li Xinyuan was later found on the ground outside the building, unconscious and covered in blood, she said.

Footage of the attack spread widely across social media on Thursday, sparking public outrage.

Li Shuyong said he has already received 58,000 yuan ($9,500) in compensation from the 11-year-old's father, although he said it's not enough to pay for medical expenses. Calls to the 11-year-old's father were not answered.

"It costs 4,000 yuan a day and my son has been under observation for 10 days," Li Shuyong said. "Doctors said the operation will cost over 30,000 yuan."

He said the family of six earns 6,000 yuan a month. Both parents work on construction sites in downtown Chongqing.

Dan Xingming, a lawyer for the family, said it is demanding 300,000 yuan in compensation from the girl's parents.

A local court has accepted the case, he said.