The cruise giant said on Monday (17 August) the ransomware attack happened on Saturday (15 August), with the attackers able to "access and encrypt" a portion of one of its brands’ information systems.

Data files were also downloaded by the perpetrators, said the firm.

Carnival said it promptly launched an investigation, notified any relevant authorities, and had engaged incident response professionals, including "industry-leading" cybersecurity firms.

"While the investigation is ongoing, the company has implemented a series of containment and remediation measures to address this situation and reinforce the security of its information technology systems," said Carnival.

Based on a preliminary assessment, Carnival said it expected the attack to have included unauthorised access to personal data of guests and employees.

"Although we believe no other information technology systems of the other company’s brands have been impacted by this incident based upon our investigation to date, there can be no assurance other information technology systems of the other company’s brands will not be adversely affected."

Carnival has not disclosed which of its brand was impacted by the attack.