Five endangered monkeys worth several hundred pounds each have been stolen from a zoo as they slept, possibly in response to an increasing demand for exotic pets.
Thieves smashed through fencing at Drusillas Zoo Park at Alfriston, East Sussex, and stole the marmosets from their nesting boxes, park officials said.
There was concern today that the primates - normally found in the South American rainforests - could have been stolen to order for illegal collectors of rare animals.
Sue Woodgate, the zoo manager, said they were particularly anxious to trace the mother monkey, a silvery marmoset called Jazz, who needs regular medication.
"We are very worried about the welfare of all the monkeys, especially Jazz, who has a medical condition which requires treatment twice daily," she said.
"She will become very poorly quickly without her medication."
Also missing is Larkin, the first silvery marmoset baby born at Drusillas.
The marmosets were safe in their enclosure at the popular visitor attraction when zoo staff locked up on Saturday evening.
But when keepers returned yesterday morning, they found smashed glass, broken fences and the marmosets missing.