A woman has been declared missing after being seen at the Exchange Hotel in Mossman three weeks ago. 

The family of Karin Anni Sosna, 62, is appealing to the public for help to find her and holds grave concerns for her safety, given her fragile mental state.

Ms Sosna was last seen travelling north to Cooktown with two unknown males after they witnessed her winning money at the Exchange Hotel on February 2. 

They are said to be travelling in a white Mercedes with Western Australian plates with registration number IDUH-621.

Anyone with any information is asked to contact Mossman Police Station.