Dodgy dealings by a man named Dave have prompted a warning from Hastings police.

They say people should be alert to the man who is approaching retailers, publicans and customers, offering seafood and livestock for sale.

But the goods offered never turn up, said Hastings Senior Sergeant Dave Greig.

"This person has made several such offers in the past few days," he said.

"His modus operandi is to offer crayfish or livestock for sale, to ask for cash up front, and then make arrangements for delivery later that day or the following day."

But the seafood or livestock are never delivered, Mr Geig said.

The man is described as a casually presented Caucasian in his mid-to-late 40s, with olive skin. He is about 1.8m (six feet) tall and has short dark hair. On at least one occasion he has identified himself as "Dave".

Mr Greig said anyone approached by the man should contact Detective Wayne Steed at Hastings police.