Exotic skins have crawled back on to catwalks and snakeskin "it" bags are achingly fashionable: Kylie Minogue heaves around a python-skin Zagliani holdall and Eva Longoria brandishes a Prada python-skin bag.

The EU, led by Italy, is the world's biggest importer of reptile skins, buying €100m (£69m) worth in 2005. Fashion houses claim they use "farmed" skins and work within the international convention that restricts trade in endangered animals.

Several US crocodile ranches try to kill their animals humanely according to Clifford Warwick, a consultant biologist who has studied the reptile trade for 30 years, but there are no proper snake farms: snakes take too long to mature and are too expensive to rear in captivity.

More than 350,000 skins and leather products of the reticulated python species alone were legally imported into the EU in 2005; conservationists estimate the illegal trade is just as big.

"I'd love someone to show me the farms that are raising so many adult snakes a year," says Warwick. Instead, pythons are hunted in Indonesia and Malaysia, and species are threatened. "We are seeing smaller and smaller snakes caught and hunters having to travel across wider areas; classic signs of a species in decline," he says.

There is also spectacular cruelty. Skin shed by snakes is too thin for bags, so snakes must die for their skins. Larger captured snakes are often first starved to loosen their skin and then stretched by being forcibly pumped with water. Snakes are routinely nailed to a tree and skinned alive, their bodies thrown on to heaps where they can take two days to die.

"There's no such thing as an exotic ethical skin," says Yvonne Taylor of the animal rights campaign Peta. "You can have the killer-look without the killing by opting for a fake version."