Happened yesterday across from me. What a horrible way to go 
A crewman who died after running out of oxygen in a ship's ballast tank did not have the usual breathing gear, the BBC has learned.
The Filipino collapsed and died on the Saga-owned cruise ship in Southampton on Wednesday. A second man was rescued.
The pair inspected the tank without a safety officer or written permission, which is required by Saga due to the low air levels, a source told the BBC.
Police are investigating the suspicion of gross negligence.
Detectives are examining whether the men were told to enter the ballast tanks or told to inspect them from a safe distance above.
Saga confirmed various guidelines should be followed during the procedure.
These include ventilating the tanks well in advance and anyone wanting to go inside must have written permission and be accompanied by a safety officer as it is an out-of-bounds area.
Saga said it would not comment on whether these procedures were followed.
Fire crews spent more than an hour battling to save the man, who was in his 40s. His body has been recovered.
The other man, in his 30s, was taken to hospital in a "confused" state but later released, police said.
The cruise ship, which holds 600 passengers, had been due to set off for a cruise at 1600 BST on Wednesday.
The passengers have been onboard overnight and were being informed of events, Saga said.
An investigation is also being carried out by the Marine Accident Investigation Branch, which has a team of five at the scene.

A crewman who died after running out of oxygen in a ship's ballast tank did not have the usual breathing gear, the BBC has learned.
The Filipino collapsed and died on the Saga-owned cruise ship in Southampton on Wednesday. A second man was rescued.
The pair inspected the tank without a safety officer or written permission, which is required by Saga due to the low air levels, a source told the BBC.
Police are investigating the suspicion of gross negligence.
Detectives are examining whether the men were told to enter the ballast tanks or told to inspect them from a safe distance above.
Saga confirmed various guidelines should be followed during the procedure.
These include ventilating the tanks well in advance and anyone wanting to go inside must have written permission and be accompanied by a safety officer as it is an out-of-bounds area.
Saga said it would not comment on whether these procedures were followed.
Fire crews spent more than an hour battling to save the man, who was in his 40s. His body has been recovered.
The other man, in his 30s, was taken to hospital in a "confused" state but later released, police said.
The cruise ship, which holds 600 passengers, had been due to set off for a cruise at 1600 BST on Wednesday.
The passengers have been onboard overnight and were being informed of events, Saga said.
An investigation is also being carried out by the Marine Accident Investigation Branch, which has a team of five at the scene.
Comment