The Agriculture, Fisheries and Conservation Department has set up a team "to combat sales of smuggled cats and dogs on social media platforms" and it is investigating the selling of pets through online advertisements in case any are related to so-called petfishing scams.

The team is also dealing with public complaints about online pet sales and is working closely with police and customs in combating shady online sales activities.

The Consumer Council on Thursday warned people against what it called petfishing, saying many pets purchased online as a result of deceptive advertisements involving seemingly healthy and adorable pets had health problems.

Michelle Yeung, an AFCD principal veterinary officer, told an RTHK programme on Friday that people should also be cautious over pet adoption advertisements.

"These activities are highly anonymous, as scammers usually use fake accounts and instant messaging apps," she said.

"Transactions are also difficult to be traced.

"Even if they say it's not related to selling, that they are looking for someone to adopt the animals, scammers are actually trying to pique someone's interest so later they can seek money transfers."

Yeung pointed out that licensed pet stores are allowed to advertise online, but the selling of pets should be conducted at the physical venue.

She added that people can call the department to check for validity of pet licences if they have any concerns before making any purchases.

For her part, the deputy head of the Pet Trade Association, Angela Chan, said buying pets online has become a trend with people surfing the internet a lot, but that most of the online pet trade was illegal.

"Almost 90 percent of online pet sellers don't have a licence," she said.

"Some sellers claim to have bred their own animals, but the pets are actually smuggled in from the mainland.

"Some may even breed pets without owning a licence issued by the AFCD."

Chan said stores are required to renew their licence to trade every year as a way to ensure the welfare of pets.

Under the licensing conditions, stores have to abide by a code set by the AFCD, such as maintaining good ventilation and hygiene standards and providing enough space for animals to live in.