Norwegian Cruise Line Holdings will keep its 28 ships at anchor a little longer as it works through coronavirus- related requirements imposed by the US Centers for Disease Control and Prevention (CDC).

The Frank Del Rio-led owner announced it will suspend its entire fleet throughout April to give it time to come up with a "return-to-service plan" that adheres to the CDC's Framework for Conditional Sailing Order.

Stipulations within the order, which applies to cruiseships sailing in US waters for a year since 30 October 2020, include having on-board Covid testing labs and carrying out simulated voyages.

"The company will continue to work in tandem with global government and public health authorities and its Healthy Sail Panel expert advisors to take all necessary measures to protect its guests, crew and the communities visited," it said.

Norwegian's brands include Norwegian Cruise Line, Oceania Cruises and Regent Seven Seas Cruises brands. They collectively have nine more ships scheduled for delivery up until 2027.

Norwegian's shares, which trade on the Nasdaq stock exchange under ticker symbol NCLH, rose 0.8% to $25.59 by midday on Tuesday.

Fellow cruise majors Carnival Corp and Royal Caribbean Group have also further postponed virtually all of their salings in order to prepare for the CDC requirements.

New York-listed Carnival, which owns 87 ships, has pushed restarts for AIDA Cruises to the end of February, Holland America Line to the end of April and Princess Cruises to mid-May.

Flagship Carnival Cruise Line is laid up until March, while P&O Cruises brands for Australia and UK will remain at anchor throughout April and Cunard's three vessels may stay put into early June.

Costa Cruises is the only brand expected to sail again in the coming weeks, holding a re-sail date of 1 February.

Royal Caribbean does not plan to pull up anchor on any ships until at least March.