The jury foreman said jurors had some doubts, which had deterred them from returning a verdict of death by unlawful killing.

Earlier, Mr Banks said the jurors could return a verdict of death by unlawful killing if they were satisfied beyond reasonable doubt that the significant force which was required to cause a fracture of the child's skull was applied by the mother.

Sze-lok's mother, Mrs Tse Cheng Siu-mei, 25, a housewife, said after the hearing she did not understand how there could have been a lack of care since the child had been properly fed and clothed.

But she admitted she might not have spent enough time on the baby.

She said in the past, most of her time had been used up by household chores such as preparing meals for her husband, who had to wake up early and work long hours.

''I have learned a lesson from this incident and I will [spend] more time with my three-year-old daughter, Sze-yan, in the future,'' she said.

She said it had been her plan to have a second or third child when Sze-yan was aged at least seven or eight, but Sze-lok and her unnamed elder sister had arrived sooner.

A social worker told the court the unnamed baby accidentally died of suffocation when she was one month old in 1990. The medical cause of death was pneumonia.

Asked whether she planned to have more children, Mrs Tse said she would still like to have two or three more children.

Sze-lok's father, Mr Tse Kwok-hung, 32, a driver, declined to comment.

It is understood that Sze-yan is under close supervision by the Social Welfare Department.

During the three-day inquest, Mrs Tse denied causing the head injuries which killed Sze-lok.

She admitted nothing more than hitting Sze-lok's legs with her palm twice.

Mr Tse, in his testimony, also denied hitting the baby or seeing his wife hit her.

Although several doctors said Sze-lok's head injuries were not accidental, neither of the baby's parents could offer any explanation.

The court heard Sze-lok's death came 10 days after she was re-admitted to the Prince of Wales Hospital with convulsions.

She was in a coma and found to have three fractures to her skull, as well as old and new head injuries.

The girl was first admitted to the hospital on July 6 last year with convulsions.

Apart from multiple bruises, bite marks and scratches found on her body, she also had a fractured skull.

She returned home a month later.

The director of Against Child Abuse, Mrs Priscilla Lui Tsang Sun-kai, said one of the messages from the case was the importance of early identification of problems in a family.