Twelve more cruises across two ships have been cancelled by Carnival Cruise Lines in the first phase of a fleet-wide operational review following propulsion problems on four vessels.

Ten additional sailings by Carnival Triumph have been dropped after the ship was left stranded in the Gulf of Mexico last month due to an engine room fire.

The line is also postponing the entry into service in the Mediterranean of Carnival Sunshine, which is in the process of a $155 million refit and name change from Carnival Destiny.

The first two cruises by the new-look vessel between Barcelona and Venice have been dropped and it will now enter service on May 5.

Passengers booked on the cancelled cruises by Carnival Sunshine, which has been heavily promoted in the UK, are being offered a full refund, plus reimbursement for any non-refundable travel costs. They will receive a 25% discount on a future cruise.

“The additional time out of service will allow for implementation of the enhanced operating redundancies and other measures,” Carnival said.

President and chief executive Gerry Cahill said: “The changes we are implementing are focused primarily on improvements to better support continued power and hotel services should unexpected issues arise.

“Going forward, the review will focus on the balance of our fleet. While this process will take time, it is our highest priority and has the full support and resources of Carnival Cruise Lines and Carnival Corporation.”

Carnival Triumph will now not return to service until June 3 following the cancellation of ten additional cruises in addition to 12 departures from Galveston to Mexico which have already been dropped.

Full refunds, reimbursement for non-refundable transportation costs and a 25% discount on a future four- to five-day cruise are being offered to affected passengers.

Carnival said: “The cruise line is making significant investments to enhance the level of operating redundancies and the scope of hotel services that can run on emergency power, and further improve each ship’s fire prevention, detection and suppression systems.

“Given the necessary lead time to source needed materials and implement the enhancements, Carnival will extend the current out-of-service period for these two ships.”

Cahill said: “We sincerely regret canceling these cruises and disrupting our guests’ vacation plans.

“We are fully committed to applying the recommendations stemming from our fleet wide review and to make whatever investments are needed despite the difficult decision to impact people’s vacations.

“Our team of experts has worked virtually around the clock to determine the best set of solutions and rapidly develop an effective implementation plan for both of these ships. Moving forward, we will have the ability to source materials and schedule improvements much more expediently, thus minimising the scheduling impact on other vessels.”

He added: “I would like to provide continued assurances that all of our vessels have fully effective safety systems, equipment and training in place.

“Additionally, our ships receive regular inspections from the United States Coast Guard and other regulatory authorities. “In addition, we are applying new learnings and making enhancements in the area of fire suppression and extinguishing.