LONDON - Scientists are calling for an urgent protection of cheetahs, as the world's fastest animal is on the brink of extinction due to habitat loss and human activities, according to a study published Monday.

There are only 7,100 cheetahs worldwide, and their population has declined rapidly since late 1990s, as human encroachment has pushed the wide-ranging predator out of 91 percent of its traditional habitat, said the study published on the journal Proceedings of the National Academy of Sciences.

In Zimbabwe, for example, the cheetah population declined from around 1,200 in 1999 to just 170 in 16 years, said the study led by Zoological Society of London, charitable organization Panthera, and Wildlife Conservation Society.

Consequently, the cheetah should be re-categorized as an "endangered" species instead of the less serious "vulnerable" species on the International Union for Conservation of Nature's Red List of Threatened Species, the study said.

Cheetah is one of the widest-ranging carnivores, running across lands far outside protected areas. About 77 percent of cheetah habitats fall outside of protected areas, leaving these big cats extremely vulnerable to human pressures, the study said.

"Given the secretive nature of this elusive cat, it has been difficult to gather hard information on the species, leading to its plight being overlooked," said Dr Sarah Durant from the Zoological Society of London, a lead author of the report.

"Our findings show that the large space requirements for the cheetah, coupled with the complex range of threats faced by the species in the wild mean that it is likely to be much more vulnerable to extinction than was previously thought," Durant said.

Besides habitat loss, cheetahs have also suffered from conflicts with humans, including illegal hunting and trafficking of cheetah fur, illegal trade of cubs, loss of prey killed by villagers for meat, as well as road accidents.

More than half of the world's cheetahs live in southern Africa, which is sparsely populated. Cheetahs have been virtually wiped out in Asia, save for fewer than 50 in Iran, according to the study.

"The take-away from this pinnacle study is that securing protected areas alone is not enough," said Dr Kim Young-Overton, director of Panthera's Cheetah Program and author of the report.

"We must think bigger, conserving across the mosaic of protected and unprotected landscapes that these far-ranging cats inhabit, if we are to avert the otherwise certain loss of the cheetah forever," she added.