Trade Me says it's working hard to make sure it can shut down any puppy mills that appear on its website.

Puppy mills are large-scale commercial dog breeding operations that animal rights group, Paw Justice, believes are up and running on Trade Me.

Trade Me's manager of trust and safety, Jon Duffy, says it's working with the SPCA on a code of conduct for sellers.

"We will be keen to take measures to improve our processes if, at the end of this, we're deemed to need this."

Duffy, says they are open to help from members.

"If people have evidence that there are puppy mills out there that are reaching animal welfare standards we're keen to know about it."

Jon Duffy says Trade Me is working on a code of conduct for sellers.