Carrying Zulu warrior shields and draped in leopardskin, the men of South Africa's Shembe church move hypnotically as they go through the steps of a traditional religious ritual.

But the spotted pelts around the dancers' chests are slowly being swapped for faux fur, under a pact between conservationists and church leaders.

Leopards' skins are a symbol of pride and royalty in the Shembe religion, which was founded a century ago in the eastern KwaZulu-Natal region and has roots in Christianity and Zulu customs.

However, with the big cat populations threatened by loss of habitat and poaching, Shembe leaders have backed a cheaper and more predator-friendly alternative that still upholds tradition.

"The leopardskin has got a significance because it shows power," said Lizwi Ncwane, spokesman for the church officially known as the Nazareth Baptist church. "For the past four months now, we have been using fake skins because we are trying to bring awareness among our people," he said.

The religion has more than five million members, tens of thousands of whom flock to a special service every January at which older men move to the rhythmic sound of drumbeats and low trumpets.

"That is the way we worship God: we worship through prayers as well as dances," said Ncwane.

Participants must wear the colourful ceremonial dress, which includes a loincloth of monkey tails, a leopardskin belt, elaborate headgear with ostrich feathers, and above all a cape of leopardskin slung across their chests.

"It represents being the king," explained a mineworker, Sphiwe Cele, who says he paid 4,500 rand (£250) for his legally hunted authentic leopard skin.

"Of course, we are not the king of the Zulu, but Shembe said we are the kings of our homes, so we must wear this today when we go to the traditional gathering," he said.

In a country where leopard-hunting permits are affordable only for the very rich or foreign tourists, conservation groups dispute that the trophies worn at Shembe gatherings are legal.

"This is the biggest display of illegal wildlife contraband on Earth," said Guy Balme, Africa leopard programme director with the US-based conservation group Panthera. "Everything you see here is totally illegal," he said at one of the dances as music rang out in the background.

Most of the skins came from poachers in South Africa and neighbouring Mozambique, Zimbabwe and nearby Malawi, he said.

Listed as "near threatened" on the International Union for Conservation of Nature's (IUCN's) red list of threatened species, leopards number between 5,000 and 7,000 in South Africa today, according to the director of the conservation group Landmarks Foundation, Bool Smuts.

"They certainly are on a distinct decline," he said, warning that no official figures exist.

To stem poaching, Panthera in recent years has worked to develop authentic-looking fake leopard skins and to convince the Shembe to use them.

Some less-well-off dancers were already wearing a form of fake fur with cow and impala skins painted with leopard spots, said the leopard programme co-ordinator, Tristan Dickerson.

"So I thought, 'Well, if I came up with a realistic version, maybe we can introduce it to the church.'"

The fabric is produced in China and then shipped to Durban, where it is sewn into the final product.

"It has taken four years to get to the point where we are now, where they are accepting the furs and they are using them," said Dickerson.

Panthera aims to distribute 6,000 mantles – free, for now – by mid-2014, and has already given out a third of that.

About 10% of members' furs are now estimated to be fake, since the church threw its weight behind the initiative.

Donning his own synthetic leopard fur, Ncwane suggests that up to 70% of dancers will have given up real skins within two years.

Later, loincloths, bracelets and belts will follow, costing much less than the full natural fur regalia, which costs up to 15,000 rand.

"It has become a kind of a trend," said John Smith, a Panthera volunteer. "At the beginning, some were very rude and told me they didn't need those needless blankets. It was then endorsed by the church."