More than 100 puppies have been seized at Kent’s Channel ports in three months, prompting calls from the Dogs Trust for more enforcement.
The charity, which has been funding the care and quarantine of illegally-landed puppies since December, said 150 had been seized and it had rehomed 94.
Government minister George Eustice, who leads the Animal and Plant Health Agency, said people were being caught.
Defending enforcement, he said an intelligent-led approach was working.
He also said government figures showed 108 puppies had been seized since 2 December.
The Dogs Trust has reported a surge in puppy smuggling and said demand had grown for designer breeds, such as Pugs, Dachshunds and French Bulldogs.
Adam Levy, from the charity’s Canterbury branch, called for the age limit for any puppies brought into the country to be raised to six months, to prevent tiny animals being transported and also make it easier to identify breeds.
He also called for increased resources and more checks at the border.
The trust has urged buyers to carry out checks before buying a puppy.
Mr Eustice said: “A small number of unscrupulous vets were issuing fraudulent paperwork and our veterinary officers wrote to authorities in those other European countries to raise the alarm.
“There’s another separate issue which we’re starting to pick up which is we may have some puppies being brought in where nobody’s getting the paperwork at all.”
Mr Eustice said checks were carried at the border and officials were always available.
He said: “I suspect actually there’s a relatively small number of traders that are bringing these puppies in but you only need a small number to bring quite a lot of puppies across the border.
“If we can have an intelligence-led approach, identify those people, bring them to justice, we’ll be able to tackle this problem.”