A search and recovery operation is underway after items including ammunition were found discarded off Maryport Harbour.
The found items, which also included firearm components, have been safely secured by police.
But officers are concerned people might have picked up ammunition or parts before the discovery and taken them home, posing a potential safety issue.
Searches are underway to see if any other ammunition might still be on parts of the beach only visible at low tide.
The items are not linked to criminality at this time.
Temporary Superintendent Andy Wilkinson said: “It may be members of the public have picked up some of these items out of curiosity.
“If they have, we would encourage them to get in touch with us and we could come and take these items away safely.
“Search teams are looking and it may be we utilise the assistance of underwater search teams during this recovery operation, so the public may see such a presence at the harbour.”
Anyone with any information should call police on 101, referring to incident 301 of May 8.