Indonesia is returning 17 rare pygmy kangaroos to the Papuan rain forest after rescuing and acquiring them in recent years from illegal traders and private zoos, officials said Monday.

It is unknown how many of the mammals, which can grow up to three feet long and weigh 25 pounds, still survive in the wild.

The animals being released were born to six males and females cared for by the Cikananga Animal Rescue Center on West Java where they have been reared to survive in their natural habitat, said spokesman Resit Sozer.

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They are to be released on Tuesday into the forest, where they will face predators such as giant pythons and local poachers who eat their meat or sell their hides.

The World Conservation Union placed the species in its "vulnerable" category, meaning they face a high risk of extinction in the medium-term. It has not specified a time period.

The trade in rare and exotic animals from Papua and other areas of Indonesia is rampant, due largely to poor law enforcement.

Rapid deforestation and commercial development also threaten species such as the Sumatran tiger, elephant, rhino and orangutan.

"Illegal trade can't be stopped without the cooperation of buyers and neighboring countries. If the buying continues, we will never be able to stop it," said Adi Susmianto, a senior official at the Forest Ministry.

Little is known about the Indonesian kangaroos, known as dusky pademelons, or Thylogale brunii.

They belong to a family of seven kangaroo-like mammals and are generally found in forests in the southeastern coast of the island of Papua, split between Indonesia's West Papua province and the nation of Papua New Guinea.