Mandy Moore has pleaded with fans to keep an eye out for her brother's missing cat.

The 33-year-old 'This Is Us' star has taken to Instagram to post an appeal to her 2.4m followers to help her find her brother's missing cat Claudia, who escaped from an open door at the start of this week.

Writing on the photosharing site alongside a picture of Claudia, Mandy wrote: ''Attention LA Koreatown folks: my brother's cat Claudia is missing and he's away for work in Alaska and it's desperate for any help finding her.

''Here's some more info and if you've spotted her or have any info, please email deffufa@gmail.com. Thank you!!

''Claudia a very sweet is a 12 year old domestic shorthair and is small in size. She is grey and white cat with green eyes and grey ringed tail.

''She has a very distinctive meow. She escaped from an open door Monday night, 3/26, from the 500 block of St. Andrews near 6th street in Koreatown.

''She is an an indoor car and is not used to being outside. She is normally very friendly, but may be scared and skittish.(sic)''

Mandy has two openly gay brothers - Scott and Kyle - and their mother Stacy left their father a decade ago to be with a woman and in October, the actress revealed that she is ''extraordinarily close'' to her family and they don't have any secrets.

She said: ''Nobody is hiding who they are. There are no secrets in our lives. I love and support my mom and my brothers with my whole heart.

''And nothing makes me happier than seeing anybody live their authentic self, and to choose love. If anyone can find love, I support it, I salute you and I celebrate that.''