A four-week-old rare pygmy marmoset monkey along with an adult male named Gomez and a nine-month-old female named Sophia were stolen from their enclosure at a wildlife park south of Sydney. The staffs of the park found the trio missing from their enclosed space at the Symbio Wildlife Park in Helensburgh on Saturday (26 November) morning.

Police were called to the park after the incident and they have made a public appeal, especially for the baby monkey as "is at a particularly fragile age and needs to be reunited with its mother in order to be fed", police said.

They have urged the local public with any information to call Crime Stoppers on 1800 333 000 .

John Radnidge, the owner of the wildlife park, said it was a "desperate situation".

"It's terrible to have three stolen from us. But one's only a baby, it's only four weeks old, it's reliant on its mother's milk to survive. It needs to come back here, or be handed in to a vet or the police," Radnidge said.

Radnidge appealed to the people to help him find out the missing animals. He said whoever had taken the monkeys to "do the right thing and return them to where they belong so they can get the care they need, otherwise these animals will die.

"That would be an absolute tragedy and totally unnecessary."

"These are animals that require specialised diets. The baby won't live and the others will be so stressed.

"They will simply die unless they're returned; there's no benefit to anybody not having them with us," the wildlife owner added.

The pygmy marmoset is inhabitant to South America and one of the smallest primates in the world. It weighs just over 100 grams.

They are merely the size of a human thumb at birth; and need constant attention and must feed every couple of hours.

However, this is not the first time Symbio Wildlife Park has experienced this. Earlier in 2010, four pygmy marmoset monkeys and four cotton-top tamarins were stolen from their enclosures. Of which, three of the tamarins were recovered soon.