The half-tame beasts are released into enclosures, then briefly roam until the hunter's sights settle upon them and the rifle fires. But killing lions specifically bred to satisfy the demand of rich foreign trophy hunters may be about to end.

The fate of thousands of these lions will be decided on Monday as judges in the South African high court consider an appeal by an influential breeders' lobby. An end to the controversial practice of "canned hunting" would be hugely welcome to animal welfare groups. But it would also raise the prospect of the mass slaughter of the 5,000 big cats, which could not be released into the wild.

Steve Smid from Animal Rights Africa says even healthy, young lions could be euthanised because there is not enough space in national parks or private reserves to accommodate the territorial animals. A mass release could also endanger humans. "Somewhere along the line, these animals are going to be dumped," he said. "There is no capacity in the wild, so we come to the unsavoury option of having to euthanise them."

South Africa passed a law that effectively banned canned hunting in 2006, but successive legal appeals have meant business as usual for the estimated 120 captive breeding centres in the country. The first challenge by the South African Predator Breeders Association (Sapba) against the regulations failed in June, but the association quickly filed another appeal, which will be heard on Monday.

"While the appeal is still with the courts, we are still continuing to hunt in this way," said Carel van Heerden, Sapba chairman.

Will Travers, the chief executive of Born Free, a charity that campaigns for the welfare and treatment of lions, said: "The breeders are dragging out the legal process and making as much money as they can while the ban is suspended."

The National Environmental Management Biodiversity Act (Nemba) of 2004 provided regulations on "threatened or protected species" that included lions, and that were introduced in 2006. Sapba challenged the inclusion of lions, arguing the new requirement to allow lions to roam free for 24 months before being hunted in a "fair chase" would destroy their industry and local economies.

As well as supporting a multimillion-dollar hunting industry, the lion breeders claim their centres play an important role in conservation. "The more international demand for the hunting of large predators can be satisfied through the hunting of captive bred animals, the more the pressure will be taken of the free roaming populations," said Van Heerden.

Campaigners claim canned hunting is "immoral" and "barbaric". They say that, unlike in well-managed trophy hunts of wild animals, there is no "fair chase" . They also claim that to ensure the lions are semi-tame, breeders often remove cubs when just a few days old, causing great distress for the lioness and inducing another oestrus cycle to make her more receptive to mating. Sometimes female cubs are culled at the expense of their male siblings, as hunters prefer to kill males because of their impressive manes.

South Africa is the centre of the canned hunting industry. Each kill costs about $60,000 in total, including skinning, treating the hide, and the export licence needed to take it home. It is estimated that around 1,000 lions are killed on canned hunts each year, many of them by American tourists. When the lions reach maturity, they are released into enclosures of around 100 acres, a very small area compared with the animal's natural territory of 10,000 to 50,000 acres.

Canned hunting also divides opinion within the trophy hunting industry. In Namibia, the practice is outlawed. Marina Lamprecht, who owns Hunters Namibia Safaris and sits on the board of the Namibia Professional Hunting Association, said: "We condemn canned hunting in the strongest possible terms as an industry and as a country. It's a pity that people are willing to sacrifice ethics for US dollars. It's a small minority that gives everyone a bad name."

The hunts she runs operate an "ethics" policy, under which most of the animals are very old – well beyond reproductive age – and the hunts must involve a fair chase.

Albi Modise, a spokesman for South Africa's Department of Environmental Affairs, said the government was committed to enforcing the legislation, and that breeders could not expect assistance from them. He said: "It is their responsibility to deal with the issue, as these lions are their property. However, the department will cooperate with all stakeholders and investigate all available options to address the issue should it arise. We will still continue to regulate the industry through appropriate conservation tools in order to mitigate all threats to biodiversity."