Residents within a 30-kilometre radius of Perth Zoo have been asked to watch out for.... squirrels.

Not because they are cute, but because they are posing an "extreme pest risk".

Do you live in Perth's 'squirrel' circle?

There have been three northern palm squirrel sightings recently reported to the Department of Agriculture and Food: one at Como Secondary College and two at Harold Rossiter Park in Kensington, next to Swan Tafe.

DAFWA invasive species manager Richard Watkins said WA had no native squirrels - they were feral pests.