American XL bully dogs will be added to the list of banned breeds from 31 December, the government has confirmed, as it released further details of how the ban will be implemented.

Rules coming into force at the end of year will make it illegal to breed, sell, advertise, exchange, gift, rehome, abandon or allow to stray XL bully dogs in England and Wales.

From 31 December, XL bully dogs must be kept on a lead and be muzzled in public. Owners who wish to keep their dogs will have until the end of January to register them.

From 1 February 2024, it will become illegal to own an XL bully dog if it is not registered on the index of exempted dogs, and the animals will be subject to restrictions, including having to be microchipped and neutered.

Owners who fail to comply could face a criminal record and an unlimited fine, and their dog could be seized.

In Tuesday’s announcement, the government urged owners to start training their dog to wear a muzzle and walk on a lead, and told breeders to stop mating XL bullies now in anticipation of the new restrictions.

The environment secretary, Thérèse Coffey, said: “We are taking quick and decisive action to protect the public from tragic dog attacks and today I have added the XL bully type to the list of dogs prohibited under the Dangerous Dogs Act. We will continue to work closely with the police, canine and veterinary experts, and animal welfare groups, as we take forward these important measures.”

The Dog Control Coalition – made up of the RSPCA, Blue Cross, Battersea, Dogs Trust, Hope Rescue, Scottish SPCA, the Kennel Club and British Veterinary Association – has long campaigned against banning breeds, and said it had “serious concerns about the very short amount of time in which owners have to comply with the rules”.

A spokesperson said: “There is currently no clear understanding of how many tens of thousands of dogs could fall within this breed specification, and we urge the government to ensure that the teams responsible for enforcing this law – the police and local authorities – have the resources and training they need before the ban begins to avoid any more dogs than absolutely necessary from being caught up in this.”

An official definition published by the government said the dogs had a “heavy, large and broad” head and a “blocky or slightly squared” muzzle. The breed was also described as being “heavily muscled” with a “large, blocky body giving the impression of great power for size”, and a glossy, smooth and close coat.

The RSPCA said it had left the government’s breed confirmation working group over concerns “about its approach and the potential for a larger number of dogs to be involved than was actually originally intended”.

Dr Samantha Gaines, the head of companion animals at the RSPCA, told MPs earlier this month: “I think we have to accept that there are going to be a lot of dogs that are captured within the standard that defines what this dog looks like whose behaviour does not pose risk to public safety.”

The prime minister, Rishi Sunak, described XL bullies as a “danger to our communities” when he promised to instigate a ban following a spate of attacks involving the dogs over the past year.

The government said compensation would be provided to help owners with the costs of having their dog put down by a vet if they chose to do that.

Experts have reported that owners have already started asking vets to put down XL bully dogs in anticipation of the ban, because of concerns about what the restrictions may be and how they could affect things such as tenancy agreements.