BEIJING (AFP) - A Chinese mother threw her newborn girl out of an apartment building window to the ground, where she was run over by a car, media reported on Thursday.

Surveillance footage from Harbin in the northeast showed a bag containing the baby hitting the roadway outside, then crushed by a vehicle. It was aired by a Heilongjiang provincial TV station.

The mother - an 18-year-old hair salon worker surnamed Zhang - gave birth on Tuesday in the bathroom of a second-floor apartment that she shared with nearly 10 people, the official provincial Shenghuo Newspaper said.

In her weakened state she walked upstairs to a window between the second and third floors, and tossed out her daughter.

It was not clear whether the baby was killed hitting the ground, or by the impact of the car.

She was no longer breathing by the time a security guard noticed the bloodstained bag and called police.

Zhang was held on suspicion of intentional homicide and taken to hospital for treatment, where her mother told her: "How could you do this, this is murder!" the Shenghuo paper reported.

It did not say whether the car driver was being sought.

One user of Sina Weibo, a popular microblog, told the mother: "The child is innocent. The loss will haunt you all your life."

Incidents involving suffering infants have scandalised the Chinese public in recent years. In May a newborn baby in the eastern province of Zhejiang survived after being dropped down a toilet pipe by the mother.

The case triggered widespread fury but was later declared an accident.

In the same month a man from Jilin in the northeast was sentenced to death for strangling a two-month-old baby after stealing a vehicle with the infant inside.

In 2011, a two-year-old was left lying on the street in southern Guangdong after being struck by two vehicles while passersby ignored her in 2011. The child later died.

The event unleashed public anger but also soul-searching about fast-changing social mores.