The Royal Navy has announced an investigation into how sailors were hospitalised as a result of drinking contaminated water on their ship.
The frigate HMS Portland was diverted to Portsmouth naval base on Friday after the discovery that the “wrong chemical” had entered the ship’s system to convert seawater into drinking water.
Almost all of those taken to hospital after the incident have been discharged and all are expected to make a full recovery.
A navy spokesperson said: “The recent issue with contaminated water in HMS Portland will be investigated thoroughly.
“Nearly all involved have been discharged from hospital. All are expected to make a full recovery.
“We take the health and welfare of our people very seriously and will review processes to ensure this does not happen again.”
Those affected were taken to Queen Alexandra hospital in Portsmouth on Friday.
The situation was understood to have been caused by “human error” and the person “owned up straight away”, a Ministry of Defence source said previously.
The source told the Telegraph: “The individual made a mistake and informed their chain of command. It’s really unfortunate, and their integrity should be acknowledged.”
Fewer than 30 personnel were affected by drinking the contaminated water, the source added.
The warships use fresh-water reverse osmosis, and it is understood that on this occasion the wrong chemical was used.
However, it is unclear what chemical contaminated the water. Scientists have already begun their investigation and have been onboard the ship.
HMS Portland departed from its home port at Plymouth on Saturday 7 January.
The contamination comes weeks after the Royal Navy announced that HMS Portland was tracking the Russian warship Admiral Gorshkov, which has hypersonic missiles, through the North Sea.
At the time the Royal Navy stressed that escorting warships through UK territorial waters and the adjacent sea areas is routine activity.
The type 23 frigate was launched in 1999 and underwent a refit in 2018, which included the installation of the Sea Ceptor surface-to-air missile system, 997 surveillance radar, 1084 navigational radar and the 2150 hull-mounted sonar, and returned to sea in March 2021.
Over the years, HMS Portland has been used in anti-drug missions in the Caribbean in 2007, as well as being deployed to tackle pirates off the Horn of Africa in 2009.
The ship also helped with disaster relief in Belize after Hurricane Dean hit the Central American country in 2007.