The US Centers for Disease Control and Prevention (CDC) said 252 of the 919 passengers currently onboard the ship have been fallen ill during the voyage.

The news has come following tests undertaken by the CDC on April 30 and May 1 when officials boarded the ship in Baltimore during the 34-night Old England to New England cruise.

Nor is it simply passengers falling ill, the CDC said eight of the 520 crew have also contracted the virus since the voyage began.

A Fred Olsen spokesperson said: “Fred Olsen Cruise Lines can confirm that a gastro-enteritis type illness has affected a number of guests onboard Balmoral’s 34-night L1608 Old England to New England cruise, which departed from Southampton on April 16, 2016.

“There are currently 15 guests who have been required to remain in their cabins, out of a total of 1,434 guests and crew onboard. The majority of guests onboard are British.

Balmoral has undergone inspections by the CDC and US Coastguard and received a US Public Health score of 91%.

“Balmoral has now left the US and is due to arrive in Saint John, New Brunswick later today. At no point has Balmoral been quarantined in any port on this cruise, and is continuing as planned.

“Fred Olsen has been undertaking extensive sanitisation measures and cleaning of the ship, following the company’s strict illness containment and prevention plan.

“It is believed that the highly contagious gastric illness was brought onto the ship, and is spread by person-to-person – or surface-to-surface – contact.

“Clusters are more commonly seen in areas where people are in close confines, such as hotels, schools and hospitals, as well as cruise ships. Most people do not report incidences, but on a cruise ship, cases are particularly highlighted.

“Commonly, the illness abates within one or two days. Those guests who are affected are asked to remain in their cabins during this time – with complimentary room service and in-room entertainment.

“Fred Olsen is co-operating fully with all the necessary maritime agencies and authorities and will continue to make e‎very effort possible to ensure the safety and wellbeing of all its guests and crew onboard, which is of paramount ‎importance.

“Fred Olsen’s cruise ships meet, at all times, the highest safety, hygiene and health standards, and comply fully with the strict requirements and inspections of their Flag State, the Maritime and Coastguard Agency and other relevant authorities.”