Johnny Depp's dogs could be put down upon their return to the United States because of quarantine laws there for animals coming from outside the country.

Agriculture Minister Barnaby Joyce raised the possibility that the two Yorkshire terriers could be considered stateless because they were not brought into Australia legally.

"The question is if he breached our laws, then did he follow the correct laws in the US?" Mr Joyce told the ABC.

"My worry is will the US let them back in? If not ... will they have anywhere to go?"

The new concerns come as the two small dogs are set to leave the country in a private jet.

"I'm informed that Pistol and Boo are preparing to fly on a private jet back to the United States, which is the best news that I've got," Mr Joyce said.

"Obviously there's an investigation as to how they came out into Australia."

The Department of Agriculture will issue export certificates for Pistol and Boo in an effort to make it easier for them to re-enter the United States.

"Given that Australia is considered to be free of rabies and that the United States has different certification requirements to us, we don't anticipate that the dogs will have any issues re-entering the United States," a statement read.

Depp has not spoken publicly about the debacle, but is expected to be quizzed by quarantine officials to determine how the dogs were allegedly smuggled into the country.

The Oscar nominee is expected to face a massive fine for bypassing customs to bring in the dogs.

Should Johnny Depp face legal action for not declaring his two dogs to Australian quarantine authorities? Yes 55794 No 15589