Police are urgently trying to identify a critically-ill elderly woman who was found collapsed on a footpath south of Perth late on Saturday afternoon.

The woman was found on Portrush Parade Estate in the Mandurah suburb of Meadow Springs.

She is now in the intensive care unit at Fiona Stanley Hospital and is unconscious, police said.

Officers believe the woman is a local resident as she was out walking prior to her collapse.

She is described as being of slim build, with fair skin, blue eyes and medium length grey hair. She is approximately 70 to 80 years of age.

When she was found she was wearing a pair of dark coloured sunglasses, a white short sleeve patterned embroidered blouse, leggings, and soft, black slip-on shoes.

She was also wearing two rings, including a solid gold wedding band, and a silver watch on a black leather band.

Anyone with information on the woman's identity is urged to contact police.