Smuggling the world's largest land animal across an international border sounds like a mammoth undertaking, but activists say that does not stop traffickers supplying Asian elephants to Thai tourist attractions.

Unlike their heavily-poached African cousins -- whose plight is set to dominate Convention on International Trade in Endangered Species (CITES) talks in Bangkok next week -- Asian elephants do not often make the headlines.

But the species is also under threat, as networks operate a rapacious trade in wild elephants to meet the demands of Thailand's tourist industry.

Camps and zoos featuring elephants tightrope walking, playing football or performing in painting contests employ almost 4,000 domesticated elephants for the amusement of tourists.

Conservation activists accuse the industry of using illicitly-acquired animals to supplement its legal supply, with wild elephants caught in Myanmar and sold across the border into one of around 150 camps.

"Even the so-called rescue charities are trying to buy elephants," said John Roberts of the Golden Triangle Asian Elephant Foundation.

Domestic elephants in Thailand -- where the pachyderm is a national symbol -- have been employed en masse in the tourist trade since they found themselves unemployed in 1989 when logging was banned.

Just 2,000 of the animals remain in the wild.

Prices have exploded with elephants now commanding between 500,000 and two million baht ($17,000 to $67,000) per baby, estimates suggest.

The number of baby elephants "coming into the system" is far higher than would be possible "from actual breeding", said Roberts, whose group decided to stop buying elephants seven years ago and now has 26 residents.

"I cannot see a way to buy an elephant which doesn't cause another elephant to be smuggled," he added.

Between 50 and 100 wild baby or young female elephants are sold from Myanmar each year, according to estimates by British charity Elephant Family.

The group's head of conservation, Dan Bucknell, told AFP that while some trafficked elephants may be taken elsewhere, the majority enter the Thai market.

"Thailand is certainly a hub," he said.

Smuggling such a large mammal should in theory require elaborate planning to avoid the police but in reality traffickers just "do it over a normal road", said wildlife trade researcher Vincent Nijman of Oxford Brookes university.

"Elephants can be in a truck or even walk" across the Thai border in front of complicit customs officers and border guards, he said.

Demand is not only threatening the 4,000 to 5,000 wild elephants in Myanmar, but is also hitting populations in Thailand's other neighbour Laos.

Young domestic elephants are exported across the border, furthering the decline of a population of around 480 animals, said Gilles Maurer of the group ElephantAsia.

Laos, known as the "land of a million elephants", only has between 300 and 500 wild pachyderms left and Maurer said that as the domestic population shrinks, "there is a strong risk" that poachers will turn to them.

Last year Thai authorities conducted several raids on elephant camps and seized some 25 animals -- 19 remain under their protection.

"It is likely the 19 seized elephants were smuggled wild animals as their paperwork did not match up," said forest ranger Pradung Jitraon, of Thailand's National Parks department, who participated in the operation.

Activists have welcomed the initiative but are also calling for broader reforms. "The system now is so weak," said Petch Manopawitr of the World Wildlife Fund in Thailand.

Thailand needs "more control, more transparent monitoring of the population, of what they do in terms of new born elephants", he said, calling for a proper database of elephants, using DNA testing or microchips.

Such a system, he added, would allow foreigners to visit elephant camps safe in the knowledge they are not "harming or threatening the wild population".