The consumer love affair with herbal remedies could threaten natural habitats and endanger up to a fifth of wild medicinal plant species, the New Scientist magazine reported today.

It said that a study carried out by the conservation organisation WWF, to be published later this year, has warned that between 4,000 and 10,000 plants could be at risk.

"It's an extremely serious problem," the study's author, Alan Hamilton, told the science magazine.

According to research, the market for herbal remedies in North America and Europe is rising by 10% year on year. It is now believed to be worth at least £11bn.

The study's findings are based on an analysis of the number of species at risk on the World Conservation Union (IUCN) red list of threatened plants. Two-thirds of the 50,000 medicinal plants being used are harvested from the wild.

Mr Hamilton, a member of the IUCN's medicinal plant specialist group, also contributed to a report to be launched by released organisation Plantlife International next week.

Among the threatened plants are tetu lakha, a tree found in south India and Sri Lanka and used for anti-cancer drugs in Europe; an Indian root called Saw-wort, used to treat skin disorders, and tendrilled fritillary, a Chinese plant used to treat respiratory infections.

"With demand and commercialisation growing fast, the future of the wild plants which have helped most of humanity for centuries is now more uncertain than it has ever been," Martin Harper, of Plantlife, told New Scientist.

The group, which says that the problem has been looming for years, blames the herbal medicinal industry for not guaranteeing the sustainability of supplies.

"It is time for the industry to join forces with environmental organisations to ensure that herbal harvests have a sustainable future," Mr Harper added.