Urgent safety recommendations have been issued by the Marine Accident Investigation Branch after six seafarers died in enclosed spaces on ships in less than a year, two of them at Dover.

On January 18, two seamen collapsed in a store on board the general cargo ship Sava Lake berthed at Dover’s Western Docks.

The investigators said the chief officer entered the store to try and rescue the men but soon had to leave when he became short of breath and his vision narrowed. The two seamen had been asphyxiated.

The store was next to the vessel’s forward cargo hold containing steel turnings.

To allow for the drainage of sea water and the removal of cargo residue, the bellows pieces on the cargo vent trunk had been cut. This allowed a path for the air from the self-heating cargo to enter the store.

When tested, the air in the cargo hold contained only six per cent oxygen.

In the other incidents, three experienced seamen died inside the chain locker on board a rescue ship, and last month an experienced seaman died on board the cruise ship Saga Rose berthed at Southampton.

The MAIB is due to publish reports on the fatalities on board Saga Rose and Sava Lake on completion of its investigations.

It is thought that there have been more than 120 such deaths in the past 17 years.

The MAIB has blamed complacency, lack of knowledge, potentially dangerous spaces not being identified and would-be rescuers acting on instinct and emotion rather than knowledge and training.

A range of recommendations have been made to ship owners and managers, industry bodies and the Maritime and Coastguard Agency.