The search for a crew member from Brecon, reported missing from his vessel in the Mediterranean Sea, has been called off.
A search and rescue operation to find Ioan Jones, 28, began following his disappearance early on Thursday.
Mr Jones was working on board a privately-owned tanker, sailing approximately 340 miles south of Malta.
A spokeswoman for Shell, which manages the tanker, confirmed the search had been unsuccessful.
She said: "It is with regret that we can confirm that the search and rescue efforts for a seafarer reported missing early in the morning 15 May from the LNG carrier Lijmiliya have been unsuccessful.
"The extensive search and rescue operation has been called off by maritime authorities.
"The seafarer's next of kin have been informed. Our thoughts are with the seafarer's family and friends during this difficult time.
"Shell is cooperating fully with the authorities and other interested parties as part of a full investigation."
Malta Search and Rescue had been co-ordinating the search for Mr Jones and Dyfed-Powys Police had said earlier that Mr Jones was believed to have gone overboard in the early hours of Thursday.