Children wearing blue face paints have been ordered out of a zoo's monkey house after staff discovered they were scaring the animals.

Keepers of the small Geoffrey's marmosets at Twycross Zoo in Leicestershire were baffled when certain visitors made the monkeys sound warning calls and run up and down their branches.

As an experiment, one of the zoo's management volunteered to have her face painted blue and was shrieked and stared at by the monkeys as she walked through the tropical exhibit.