Pregnant actress Jenna Dewan-Tatum has written to a California official to call for justice over the alleged neglect of thousands of creatures at an animal dealing group.

The Step Up star is backing People for the Ethical Treatment of Animals' (Peta) petition for criminal charges to be brought against the state's Global Captive Breeders (Gcb) company, which bred and sold reptiles, rats and mice.

Bosses at the group, based in Lake Elsinore, California, are alleged to have neglected and abused more than 18,000 of the animals, resulting in several of the creatures dying.

A criminal investigation is underway, and Dewan-Tatum has fired off a letter to Riverside County District Attorney Paul Zellerbach to call for justice to be served.

In the note, she writes, "I was discouraged to learn that your office has yet to take any action against the owner of Gcb or its employees, despite having been presented in December 2012 with compelling evidence - including expert veterinary reports, video footage, and photos - that a huge number of animals at Gcb had died or were dying and enduring unimaginable suffering.

"As an expectant mother, I was particularly heartbroken to see photos of ailing mother rats with open wounds on their bodies who stood guard protectively over their dead or dying babies. I implore you, too, to take action and send the strong and compassionate message that cruelty to animals is taken seriously... Justice must be served for the unspeakable suffering endured by countless animals at Gcb."