A Covid outbreak on the Royal Navy’s Carrier Strike Group has struck down around 100 sailors.
Four of the nine ships, including HMS Queen Elizabeth, Britain’s new aircraft carrier, have been affected.
The Telegraph understands no service personnel aboard USS The Sulllivans, a destroyer from the US Navy, or HNLMS Evertsen, a Dutch frigate, have been taken ill.
The MoD said “routine testing” of personnel had picked up a number of positive Covid results but that all personnel had received two doses of vaccine.
A spokesperson said: “The Carrier Strike Group will continue to deliver their operational tasks and there are no effects on the deployment.”
An investigation is underway to determine the source of the outbreaks, but it is considered likely at least one sailor returning to duty from a recent period of shore leave in Cyprus is responsible.
Military sources told the Telegraph such scenarios had been anticipated and mitigation measures were in place to ensure safe isolation, and for routine activity on the ships to continue.
The Carrier Strike Group has just transited the Suez Canal and is currently in the Gulf of Aden on its 27,000 nautical mile passage to Japan and back.
HMS Diamond, a Type-45 destroyer, has been forced to return to Italy for essential maintenance having suffered engine difficulties, but is travelling under her own power.
The Royal Navy’s fleet of six Type-45 destroyers have been beset by technical difficulties since they were brought into service.
A Propulsion Improvement Programme is being rolled out across the fleet.
The MoD said HMS Diamond’s current mechanical problems are thought to be linked to the propulsion system.
A Royal Navy spokesperson said: “The UK Carrier Strike Group continues with global operations and has transited through the Suez Canal with a defensive ring of highly capable ships drawn from the Royal Navy and its closest partners.
“HMS Diamond has experienced some technical issues and has detached from the Task Group for maintenance, inspection and any necessary repairs. She is expected to re-join the Task Group.”