The number of animals and plants at risk of extinction rose in 2015 despite government pledges to improve protection, with species under threat ranging from lions in West Africa to orchids in Asia, a study showed on Tuesday.

The Red List of Endangered Species, backed by governments, scientists and conservationists, grew to 22,784 species in 2015, almost a third of all animals and plants sampled, from 22,413 a year ago, it said.

Loss of habitats, such as clearance of forests for farmland, cities or roads, was the main cause of the rise, according to the list compiled by the International Union for Conservation of Nature (IUCN).

Lions in Africa retained an overall listing as "vulnerable", one of the least endangered categories, thanks to conservation in southern Africa.

But lions in West Africa were listed in a more severe category as "critically endangered" due to losses of habitat and a decline in prey caused by human hunting, it said.

And it said there were also "rapid declines in East Africa, historically a stronghold for lions - mainly due to human-lion conflict and prey decline." Trade in bones and other body parts for traditional medicines were an emerging threat.

In 2011, almost 200 governments set a goal of preventing by 2020 the extinction of known species and reducing threats to those most in decline. No known species went extinct in 2015 but many came closer to the brink.

"We are not on track," said Craig Hilton-Taylor, head of the IUCN Red List Unit, told Reuters of the 2020 goals.

Still there were some conservation successes, such as the Iberian lynx, whose number rose to 156 adults in 2012 from 52 a decade earlier.

Hilton-Taylor said some economically valuable species were added as endangered.

The list said that practically all of the 84 species of tropical Asian slipper orchid, which are prized ornamental flowers, were threatened, mainly because of over-collection and habitat loss.

Nine of 17 species from the tea plant family assessed were also endangered because they are used for making tea and medicines or as ornamental plants and firewood.

"Losing these plants would reduce the genetic diversity of tea," Hilton-Taylor said. The plants might be valuable replacements for current species of drinking tea if environmental conditions were to change in future. – Reuters