Labour is to pledge in its animal welfare manifesto to provide more police to investigate foxhunting and hare coursing crimes.

The party plans to close loopholes in the 2004 Hunting Act that it said allow in practice the continuation of illegal hunting of foxes, hares and deer.

Its policies are intended to contrast with previous moves by the Conservatives, who got into hot water in 2017 over Theresa May’s pledge to hold a free vote on legalising foxhunting.

Tory sources said the party was not intending to make the same mistake again this time and its manifesto will make clear that Boris Johnson will not seek to overturn the hunting ban.

However, Labour will go further when it officially unveils the plans on Tuesday, with a promise to tighten the law around hunting.

The shadow environment secretary, Sue Hayman, said Labour would bring animal welfare policy into the 21st century “while the Tories continue with their mass slaughter of badgers and flip-flop on bringing back foxhunting”.

She added: “We are calling time on those who have been allowed to get away with illegally hunting, maiming and killing wild animals such as deer, hen harriers, foxes and hares.

“By increasing the number of wildlife and rural police forces across the country, we will help protect both wild animals and property in rural communities, and ensure a crackdown on the types of crimes against animals that this Tory government has turned a blind eye to.”

The pledge to increase policing of wildlife crimes will be supported by a £4.5m funding boost, doubling officer numbers from 88 to 170.

They would be tasked with targeting offences including hare coursing, which is a problem across farmlands, and acts outlawed by the Hunting Act, such as stag hunting, badger and raptor baiting, livestock theft and dog fighting.

The party also promised stricter rules around foxhunting, including a “recklessness” clause that would prevent trail hunts being used as cover for the illegal hunting of wild mammals.

It would remove the exemption for “research and observation” hunting and another for the “use of dogs below ground to protect birds for shooting”.

Labour said it also wanted to review the penalties for breaches of the Hunting Act and consult on the introduction of jail terms for illegal hunting.

In response, George Eustice, the Tory farming minister, highlighted his party’s record on animal welfare, claiming Brexit would mean the UK could ban the live export of animals.

“The UK is a global leader when it comes to animal welfare, and outside the EU we will be able to go even further – including proposals to ban the live export of animals,” he said.

“We have already introduced one of the world’s toughest bans on ivory sales, introduced compulsory CCTV in slaughterhouses and overhauled laws on a number of animal-related licensing schemes including regulations on the licensing of puppy breeders.”

Martin Sims, a former head of the police’s National Wildlife Crime Unit and now director of investigations at the League Against Cruel Sports, welcomed Labour’s plans, which he described as “bold”.

“I urge other parties to stand united against hunting, to pledge to finally stop the barbaric chasing and killing of foxes with packs of hounds that still takes place today, 14 years after the foxhunting ban came into force,” he said.

“Introducing custodial sentences for foxhunting would bring it in line with other animal welfare crimes, and will serve to be a more effective deterrent to those who insist on continuing to kill animals for ‘sport’.”