HUMAN remains appear to have been found at Kin Kin in Western Australia's southwest, where a bushfire continues to burn.

Police recovered what they believed to be human remains from a burnt-out structure late last night, spokeswoman Susan Usher told Fairfax Radio.

Arson squad officers are at the scene and inquiries will continue.

The fire at Kin Kin, near Manjimup, has burnt through 1280ha after being sparked on Tuesday.

A "watch and act" warning remains in place for the Kin Kin area, and Andrew and Cardac state forests in the shires of Manjimup and Nannup.

The fires have been contained but are not under control.