P&O Cruises has cancelled all trips until November 12 as well as two with longer itineraries due to begin in January 2021.
The firm had previously cancelled sailings until October 15.
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The UK’s largest cruise line said this was due to the Foreign and Commonwealth Office advising people to avoid cruises because of the coronavirus pandemic.
Customers with affected bookings will automatically receive credit for a future sailing worth 125 per cent of the cost of their original trip. They can also request a cash refund.
P&O Cruises president Paul Ludlow said: “It is clear that whilst the guidance is in place it is not advisable for us to resume operations.
“As well as cancelling all cruises up until November 12, we will sadly also be cancelling Aurora’s Caribbean and South America Adventure and Arcadia’s World Cruise.
“Given long-term planning, combined with the complexity and length of these long-haul itineraries and evolving border restrictions, we need to ensure that we adhere to the guidance as it stands.”
He added: “I know that these January cruises, in particular, are holidays of a lifetime and we are so sorry for the disappointment that these cancellations will cause.”
Mr Ludlow said P&O Cruises is working in partnership with public health agencies, the Department for Transport and industry body Cruise Lines International Association.
He went on: “We will follow all applicable guidelines to enhance our already stringent measures to keep our guests and crew healthy and well, and we will not resume sailing until this approved framework is in place.
“Fundamentally, we will be adopting best practice within the travel industry.”
The FCO’s advice in relation to cruise travel has been in place since July 9.
“The good news is that confidence in cruising is strong and we are seeing increasing and significant demand from our guests,” Mr Ludlow said.
Travellers are already booking their next cruise holiday, despite the coronavirus crisis.
A study has found an increase in demand for cruise trips in 2021.