Natalie Portman has adopted a rescue prison dog.

The 'Black Swan' star, her husband Benjamin Millepied, kids Aleph, eight, and Amalia, two, and their other canine companion Penny have welcomed mixed breed pooch Sunday into their household.

Sunday was adopted from the Paws for Life K9 Rescue organisation, which takes dogs from California shelters that are in need of training or socialisation and places them with trainers who are incarcerated in jails in the state.

Their website said: ''We do this because they can dedicate all of their time to their rehabilitation.''

Natalie shared a photo of Sunday wearing a black bandana and wrote on Instagram: ''So grateful to all the people @pawsforlifek9 who trained Sunday, the newest addition to our family! Paws for Life is a prison dog training program for PTSD service dogs and CGC certified adoptable dogs. I saw first-hand how their program is healing for both the trainer and dog.(sic)''

The 38-year-old actress is a big animal lover and recently explained how she went vegan to avoid animal products altogether, having previously been vegetarian.

She said: ''I was vegetarian before, and had eaten eggs and dairy and I thought, 'that doesn't really hurt animals, it's a natural bi-product of an animal' which I still believe if you're on a nice farm and have a few chickens, but the vast majority of animals are raised in such devastating way.

''It's devastating for the animals of course, but also for the environment. I was changed by it and it made me feel that it was urgent to, not just change the way I was, but also to spread the word.''