Defence Secretary Ben Wallace confirmed on Thursday that COVID-19 cases had been found on four vessels within the UK-led Carrier Strike Group, adding that all personnel deployed on the operation are fully vaccinated.
A Ministry of Defence (MOD) spokesperson said: "As part of routine testing, a small number of crew from HMS Diamond have tested positive for COVID-19.
"There are strict procedures in place to implement COVID guidelines on board all Royal Navy ships.
"Affected personnel are under medical supervision and are isolating.
Watch: Forces News was told that port visits for personnel are a 'human requirement', after several vessels on the Carrier Strike Group 21 deployment reported positive COVID cases.
"The remaining crews are following appropriate guidelines," they added.
Meanwhile, 54,742 personnel are yet to receive a COVID-19 vaccination.
HMS Diamond last week separated from the Carrier Strike Group after experiencing "technical issues".
The MOD said the Type 45 vessel had detached from the formation to undergo "maintenance, inspection and any necessary repairs", but was expected to rejoin the deployment.