Police say they will revisit the Longwood forestry block after "areas of interest" were identified there during a search at the weekend for missing Otautau man Dale Watene.

Mr Watene was last seen in Otautau on the evening of Thursday, April 16, and grave concerns are now held for his well-being.

The Longwood forestry block area was the subject of an extensive search for Mr Watene on Saturday (May 16), with 30 Land Search and Rescue volunteers from Southland Otago involved.

Detective Sergeant Chris Lucy said police continued to ask anyone who has information that might assist the investigation to contact them.

"We also want to hear from members of the public who notice anything of interest in the Longwood forestry block."

Anyone with information is asked to please contact Detective Sergeant Chris Lucy on (03) 211 0400. Alternatively, information can be passed anonymously to Crimestoppers on 0800 555 111.