LONDON (REUTERS) - Nestle's Purina brand is launching a line of pet food using insects, as the world's biggest food group tests more environmentally sustainable protein sources.

The move addresses a trend of people seeking more eco-friendly or allergen-free diets for their pets, and puts the world's largest food company into potential competition with smaller brands like Yora and Green Petfood's InsectDog.

The Purina Beyond Nature's Protein line, which launches in Nestle's home country, Switzerland, this month, will be available in two variations - one using chicken, fava beans and protein from black soldier fly larvae, and one using chicken, pig's liver and millet.

Both are available for dogs and cats.

In a blog post last year, the British Veterinary Association endorsed insect-based pet food, saying "insect protein offers a more sensible alternative to owners who want to offer a 'livestock-free' diet to their pets rather than homemade vegetarian or vegan diets which often result in poor pet health and welfare".