Hundreds of holidaymakers have had domestic cruises cancelled because the delay in lifting capacity constraints means ships are overbooked.

P&O Cruises, MSC Cruises and Royal Caribbean International are among the firms that accepted bookings in excess of the current 1,000-person limit.

They hoped the rule would be relaxed from Monday, but Boris Johnson’s decision to delay the end of all coronavirus restrictions for up to four more weeks means the constraint remains.

Ships operating domestic cruises are only allowed to carry up to 1,000 passengers, or 50% of their capacity if that is lower.

P&O Cruises is operating sailings on Britannia, which can normally carry up to 3,647 guests.

Kyle Hadden, a 29-year-old nurse at Wythenshawe Hospital, Manchester, was due to sail with his partner and a friend recovering from chemotherapy treatment on July 4, but their trip was cancelled despite them already being checked in and assigned a cabin.

“I don’t see the logic,” he told the PA news agency.

“We had everything. All the paperwork printed. Then they cancel it. It doesn’t make sense.”

Mr Hadden said his travelling group “have all had our challenges” during the pandemic, and it is “gutting” that their trip has been cancelled.

Sue Cole, 57, of Leighton Buzzard, Bedfordshire, who was booked for a sailing with her partner on July 18, said she is “very disappointed” with how P&O Cruises has treated its customers.

She claimed it was “bad practice” to accept bookings for more than 1,000 guests as “it was clear” that the planned lifting of restrictions on Monday “was not set in stone”.

Another affected passenger, who did not want to be named, accused the company of being “misleading” by not disclosing how many bookings it was accepting.

“The messaging led us to believe that they were only selling at 1,000 (guests), and not overbooking,” she told PA.

“It was a bit of a shock.”

The woman, who described herself as “a loyal P&O customer” for more than 12 years, said the firm should have either capped numbers at existing limits, or told guests their bookings were “at risk” of being cancelled.

“I’m disappointed with them from a brand perspective,” she added. “I expected more.”

A P&O spokeswoman refused to reveal how many bookings have been cancelled.

“Due to the Government’s extension of the passenger capacity limits placed on UK domestic cruises, we will have to ask a number of guests booked on Britannia’s early UK sailings to change their holiday dates,” she said.

Cancellations were made in reverse order from the date of a booking, so people who confirmed their plans first will still be allowed to travel.

Affected customers are being offered the option of receiving a full refund or credit for a future sailing worth 125% of the cost of their booking.

The spokeswoman added: “We are so sorry for these guests and do hope they will be able to enjoy a holiday with us later in the summer.”

MSC Cruises is only able to use a fifth of the 4,888 capacity of its ship Virtuosa, which has been operating domestic cruises since May 20.

The company said in a statement that it “had fully expected” to be able to host more guests from Monday, and is “disappointed” that the limit is continuing.

It went on: “MSC Cruises regrets that a number of UK guests who have booked a cruise departing after 21 June but before 19 July may need to be assisted to rebook on a sailing departing after the restriction is removed.”

Customers will be offered a refund, as well as other rebooking options.

A spokeswoman for Royal Caribbean International, which will operate its first domestic cruise on Anthem Of The Seas on July 7, said it “had to move some guests on our first sailings to a future sailing later in the season”.

Rory Boland, editor of consumer magazine Which? Travel, said: “Many people will be hugely disappointed by these cancellations after a long period of shutdown for the cruise industry.

“It is important that the companies involved minimise inconvenience for their customers, and ensure those who’d rather get their money back than rebook are promptly refunded.

“This shows there is still a serious risk of disruption due to changing Covid restrictions for anyone booking a holiday. We’d advise choosing a firm that offers a comprehensive flexible booking policy to give the greatest possible protection against significant travel disruption.”

Several cruise lines said they are unaffected by the extension of capacity limits, including Marella Cruises, Viking and Celebrity Cruises.