Bangkok - The birth this week of two clouded leopard cubs at the National Zoo in Washington has vindicated a Thailand-based project to raise the endangered cats as lovers from birth, a project manager said Thursday.

The Thailand-born female clouded leopard named Jao Chu gave birth Tuesday to two cubs at the US zoo's Conservation and Research Center.

It was the first births of clouded leopard cubs for the National Zoo in 16 years and the first in any North American zoo in six years.

It also marked a success for the Thailand Clouded Leopard Consortium project at the Khao Kheow Zoo in Thailand's Chonburi province, 70 kilometres east of Bangkok. The consortium sent both Jao Chu and her mate, Hannibal, to Washington last year.

"It's a really good shot in the arm," relief project manager Andy Goldfarb said.

Khao Kheow Zoo has over the past six years successfully nurtured the births of 40 clouded leopard cubs, deemed one of the hardest feline species to make reproduce in captivity.

Male clouded leopards have the unfortunate habit of killing their female mates after copulation in a caged environment.

The Khao Kheow clouded leopard project has taken a new tact in raising the endangered species indigenous to South-East Asian jungles by making sure a compatible couple is started out as friends pre-puberty and then kept together as mates in adulthood.

The romantic rearing method has proven successful in reducing clouded leopard post-mating deaths and reproducing the species.

"The latest cub was born just five days ago," Goldfarb said.

The Khao Kheow Zoo project, which is financed by the Smithsonian's National Zoo, has already sent three pairs of Thailand-born clouded leopards to US zoos. (dpa)