Police say a body has been found in Woodhill Forest, Muriwai, but haven't confirmed whether it is missing Auckland woman Carissa Avison.

A search has been underway in the forest for the missing 21-year-old, who hasn't been seen since January.

While police have yet to formally identify the body, a post on the Muriwai & Waimauku Area Community Group Facebook page made Thursday morning claimed it belonged to Ms Avison.

Police are at the scene.