An apology has been issued and refunds organised after passengers booking with Cunard, P&O Cruises and Princess Cruises raised concerns that their bank cards had been debited twice.
It is not known how many people were affected or how much money was involved after the problem came to light on Friday.
The error was traced to a third party payment processor.
There was no indication of a security breach or and personal information being compromised.
The issue affected a number of card payments made in relation to cruise bookings over an unspecified period of time.
A P&O Cruises spokesman said: “On Friday we were made aware of a one off technical error made by Elavon, our third party payment processor, in relation to card payments for cruise bookings with Cunard, P&O Cruises and Princess Cruises.
“Refunds are already being processed and we are working with Elavon at the highest level to investigate how this happened and to ensure that this could not happen again.
“Any charges incurred by guests as a result of this issue will be refunded.
“Once again we apologise to those guests who were affected by this error.”