A new ban is being imposed on travel from the US to Cuba for American group tours as well as cruise ships sailing to the island.

The move, announced by Trump administration officials, intends to roll back a US-Cuba thaw that began under former president Barack Obama.

But it is unclear exactly how the fresh Cuba sanctions rules, which take effect from Wednesday, will impact travel to the island nation.

US officials say the new rules seek to punish the country’s communist regime.

Norwegian Cruise Line tweeted to one concerned customer: “We are closely monitoring these recent developments and any resulting impact to cruise travel to Cuba.

“We will communicate to our guests and travel partners as additional information becomes available.”

Royal Caribbean announced that it is changing itineraries for June 5 and 6 sailings that were due to visit Cuba. The cruise line also said it was still evaluating the impact of the announcement.

Yacht line Variety Cruises cancelled its flagship’s 2019 Caribbean programme.

A “handful” of UK passengers have been affected by the line’s decision – all of them have been refunded and offered cabin upgrades on other sailings, Variety Cruises said.

Rather than sail to the Caribbean in November, the 36-cabin yacht Variety Voyager will reposition to Athens.

The US policy change could also affect start-up Virgin Voyages plans to feature Cuba on itineraries from Miami from next year.

Carnival Corporation, which became the first US cruise company in more than 50 years to serve Cuba in 2016 when ‘social impact’ brand Fathom docked in Havana after restrictions were lifted, confirmed its brands would no longer be permitted to sail to Cuba “effective immediately”.

Carnival Cruise Line had been sailing to the destination, while Holland America Line and Seabourn were scheduled to begin sailing in November to Cuba. Carnival said it would seek to provide details to customers currently booked to sail with the lines.

Announcing the changes, US treasury secretary Steven Mnuchin said: “Cuba continues to play a destabilising role in the western hemisphere, providing a communist foothold in the region and propping up US adversaries in places like Venezuela and Nicaragua by fomenting instability, undermining the rule of law, and suppressing democratic processes.

“This administration has made a strategic decision to reverse the loosening of sanctions and other restrictions on the Cuban regime.

“These actions will help to keep US dollars out of the hands of Cuban military, intelligence, and security services.”

The US Treasury’s Office of Foreign Assets Control said it was amending regulations to remove the authorisation for group people-to-people educational travel from the US to Cuba.

However, the changes include a “grandfathering” provision, which provides that certain group people-to-people educational travel that was previously authorised will continue to be authorised where the traveller had already completed at least one travel-related transaction – such as purchasing a flight or reserving accommodation – prior to June 5.

“Please note that travel-related transactions continue to be permitted by general licenses for certain categories of travel and certain authorised export transactions,” a statement added.

Export administration regulations are being amended “to make passenger and recreational vessels and private and corporate aircraft ineligible for a licence exception and to establish a general policy of denial for licence applications involving those vessels and aircraft”.