A domestic helper was arrested yesterday after a hidden video camera filmed her allegedly abusing a 14-month-old boy in a Sai Kung flat. The arrest was made at about 1pm after the maid's female boss, 23, checked footage of the camera installed in the living room of the second-floor flat in Sai Kung Hoi Pong Street on Sunday. A police spokeswoman said footage allegedly showed the toddler being slapped by the 28-year-old Indonesian maid. 'Bruises were found on the boy's forehead and right foot. He was taken to Tseung Kwan O hospital for treatment,' the spokeswoman said. Last night, the boy was in a stable condition. The toddler's mother told officers the film surveillance was started after the boy suffered a series of minor injuries, which the maid failed to explain. A female relative said the needle-sized lens connected to the video camera was hidden behind toys on top of a television set in the living room. The Indonesian woman has apparently worked for the family for about five months. Last night, she was still being held for questioning at Sai Kung police station. In a separate case, a Tseung Kwan O woman, 35, was arrested for allegedly injuring her Filipino maid, 39, during a dispute. Police said the woman allegedly hit the maid with a plug. The woman was treated for head injuries at Tseung Kwan O Hospital later and discharged.