The owners of a South Korean fishing vessel that sank in the Southern Ocean on Monday with the loss of 22 lives say there was no known fault with the vessel.
Five crew members from the No. 1 Insung are confirmed dead, and 17 others are missing, presumed dead.
A spokesperson for ship owner Insung Corporation, Ryan Kim, says rough seas, ice and bad weather may have been the cause of the sinking.
He could not confirm whether the longliner fishing vessel had a certificate of seaworthiness but told Morning Report there was no known fault with the vessel, which had undergone checks.
Mr Kim says another vessel from the same company No. 7 Insung is at sea and is not reporting any problems.
Maritime Union general secretary Joe Fleetwood says while it's too early to comment on why the South Korean vessel was lost, the union is concerned that it's the second such incident in recent months.
Three crew members died when the Oyang 70 sank off the South Island in August.
Mr Fleetwood says the terms and conditions for seafarers around New Zealand's coast are problematic, with minimal regulation and a lack of compliance on work and safety practices.