The model/actress has penned a letter on behalf of PETA, appealing to bosses at the company to resume its cruelty-free policy and stop paying for animal tests after they reneged on a commitment to spare animals "painful and deadly toxicity tests" by selling products in China, where nearly all cosmetics are required to be tested.

Anderson writes, "I was very disturbed to learn from PETA that M.A.C.... is selling products in China, where the company funds painful tests on animals in order to meet the country's archaic regulations.

"This has tainted the brand and alienated many of the company's longtime allies."

The animal lover was once a Viva Glam M.A.C. model.