Carnival Cruise Line will not be pulling up anchor on any ships come August after the passengership sector extended a US ports ban through September.

The Carnival Corp-owned brand in early May announced that it would return eight of its 27 ships to service on 1 August but has now pushed back that date to 30 September.

On Friday, Cruise Lines Industry Association members postponed the US Centers for Disease Control and Prevention's no-sail order for cruiseships in US territories to 15 September from 24 July.

"During this unprecedented pause in our business, we have continued to assess the operating environment and confer with public health, government and industry officials," Carnival Cruise Line president Christine Duffy said in a letter sent Monday to guests and travel agents.

"We have watched with great interest as commerce, travel and personal activities have begun to start back up, and once we do resume service, we will take all necessary steps to ensure the health and safety of our guests, crew and the communities we bring our ships to in order to maintain public confidence in our business.

"Nevertheless, we apologize for disrupting your vacation plans and appreciate your patience as we work through these decisions".

Carnival Cruise Line initially announced a voluntary 30-day pause in operations on 13 March but has now extended the lay-up for a third time as it repatriates almost 29,000 crewmembers to more than 100 countries.

Ticket-holding passengers may rebook cancelled cruises with either $300 or $600 on-board spending vouchers or get full refunds on their bookings through May 2021.

"We appreciate the patience and support of our loyal guests, and recognize how much they want to get back to cruising. When the time is right, our outstanding onboard team will be waiting to welcome them back and give them the great vacation that they deserve," Duffy wrote.

Numerous cruise brands have extended their fleet lay-ups multiple times amid the pandemic, putting the entire industry in an ongoing standstill.

Carnival's P&O Cruises most recently pushed back the suspension for its fleet to 15 October from 31 July.