The Norwegian Getaway cruise ship arrives in Port of Gdynia, Poland June 23, 2017. REUTERS/Radu Sigheti

Norwegian Cruise Line on Wednesday cancelled trips on eight ships, a few whose embarkation dates are as far out as late April, as the spread of the omicron variant in the United States shows no signs of slowing.

The division of Norwegian Cruise Line Holdings Ltd made the decision with the United States reporting nearly 1 million new coronavirus infections on Monday, the highest daily tally of any country in the world.

"Due to ongoing travel restrictions, we`ve had to modify a few sailings and unfortunately have had to cancel," Norwegian Cruise said.

The US Centers for Disease Control and Prevention (CDC) has launched investigations into 94 ships for onboard COVID-19 cases, with a few of Norwegian Cruise`s ships also under observation.

The CDC, which last week advised people to avoid travelling on cruise ships regardless of their vaccination status, starts scrutiny if at least 0.10% of the passengers test positive for COVID-19.

Norwegian Cruise, which requires all its passengers and guests to be vaccinated, cancelled all sailings on the Norwegian Pearl ship with embarkation dates through and including Jan 14.

The cruise line had also said on Tuesday it cut short a 12-day Panama Canal itinerary roundtrip from Miami on its Norwegian Pearl ship, citing "COVID related circumstances."

Norwegian Cruise has also cancelled sailings on other ships, including Norwegian Getaway, Norwegian Sun and Norwegian Spirit. It said guests will receive full automatic refunds and some bonus credits they could use for future bookings.

Norwegian Cruise has 17 vessels, according to its website.