He later woke up and found his son groaning in pain. The boy was taken to hospital where he was kept in intensive care for seven days and underwent two operations.

'Children are not the punchbags of adults,' District Court Judge Stanley Chan Kwong-chi told Lo at his sentencing. 'They are not an adult's private property. The court has to send a strong message that society does not tolerate such offenders.'

In 2006, Lo and his wife were put on 18 months of probation after being convicted of tying up and beating their eldest son, then two, with a cane.

The boys now live with foster families.