Police are appealing for the public for help to locate missing Wonthaggi man Alexander Aitchison, as they widen their search.

The 30-year-old was last seen at a Wonthaggi caravan park, but has reportedly last been seen in Brisbane in early January.

Police and his family are concerned for his welfare as he has a medical condition. Investigators believe he may be in Queensland areas such as Brisbane, Roma, Winton or Charleville.