A dog was found in a cage near Pak Mong, North Lantau, without food or water yesterday.
It was learnt that the dog had been trapped by a local group, HK Paws Guardian, as part of its campaign to sterilise stray dogs.
Under Hong Kong law it is illegal to place animal traps without AFCD authorisation.
The dog was discovered on the Tung Chung Hill track yesterday morning by a local villager, who called police.
The cage carried a notice from HK Paws Guardian asking to be notified.
An SPCA spokesperson said more than 100 illegal traps had been discovered by the SPCA and other organisations in the past two years, hket.com reported.
These traps had captured cats, dogs, wild boars and others. The spokesperson urged members of the public not to use animal traps.
After being notified, the AFCD returned the trap and the dog to HK Paws Guardian.