The global trade in python skins is often illegal and is threatening the survival of some species, says a new International Trade Centre report.
Researchers say the growing demand for handbags and other fashion items in Europe is fuelling imports.
But the trade is so poorly regulated that it is extremely difficult to establish the true source of the skins.
The authors argue that in some locations, the methods used to kill the snakes are extremely cruel.
The snake-skin business is extremely lucrative according to this report, which estimates that half a million python skins are exported annually from South East Asia in a trade worth $1bn (£625m) a year.
International agreements such as the Convention on International Trade in Endangered Species (Cites) that are designed to protect wildlife do allow for some trade in these species.
But the report’s authors say that when it comes to pythons the rules are being widely exploited. Snakes that are bred in captivity are allowed to be sold but the report finds that many so called captive pythons actually come from the wild.
The nature of the trade is such that there is a strong financial incentive all along the supply chain to use illegal snakes. A skin that a villager in Indonesia might sell for $30 (£19) will end up as a bag in fashion boutiques in France or Italy selling for $15,000 (£9,300). The highest demand is for skins between three and four metres long.
The problem is compounded by the poor enforcement of existing legislation. Illegal snake skins were hidden among legal cargoes and quotas were being ignored.
“It is up to the local authorities to enforce the laws,” co-author Olivier Caillabet told BBC News. “A lot of the time they don’t have the capacity in terms of money, people or expertise.
“And sometimes they just don’t care.”
The report argues that killing pythons on the current scale is unsustainable – many of the wild pythons are killed before their reach the reproductive stage.
Alexander Kasterine, from the International Trade Centre, which launched the study, said the threat was real.
“The report shows the problems of illegality persist in the trade of python skins and this can threaten species’ survival,” he said.
But the authors acknowledge it is a difficult case to make. Snakes don’t evoke a great deal of sympathy.
“Compared to the good-looking cuddly animals, snakes are far down the ladder in terms of how people feel about them,” said Mr Caillabet.
“To try and make the argument that the snake trade is unsustainable, for people here in Asia it’s a difficult sell.”
As well as the lack of sustainability, the report highlights cruel practices in the killing of the pythons. In many places, the preferred method is a sharp strike to the back of the skull. In Indonesia and Malaysia this method is widely used, as is decapitation.
But in Vietnam, Mr Caillabet said some people killed the snakes by inflating them with air compressors.
“It is functionally the equivalent of suffocating them, they inflate and suffocate and it kills them.” he said. “It does seem cruel and there are more effective and more humane ways of killing snakes.”
Mr Caillabet said that according to Buddhist beliefs, this method was more humane than hitting the snakes or beheading them.
The authors say that trade bans are not the best solution to deal with the problem.
They argue that a number of approaches are required to both strengthen existing laws and to try and put in place systems that would permit better tracing of python skins.
While demand for goods made of python has never been higher, the authors of the report say the European leather and fashion industries are keen to put such a system in place.
“It is incredibly difficult,” said Mr Caillabet. “We absolutely need to have a traceability system for the trade. It is very difficult if not impossible for fashion houses to tell if what they are selling is really sourced from the wild.”
The BBC contacted several luxury goods manufacturers to comment on the report, but none responded.