Carnival Corp has decided to keep two of its nine brands away from St Petersburg as Russia continues its onslaught in Ukraine.

The Arnold Donald-led owner’s Princess Cruises plans to replace 24 itineraries that call to the Russian city with voyages to “alternative ports”, it said on Thursday.

It added that “replacement ports” may include the Swedish cities of Stockholm and Visby, as well as Gdansk, Poland.

“Guests can remain booked on their long-awaited cruises, and have the opportunity to visit medieval architecture, world famous landmarks and natural beauty on these Northern Europe cruises,” Princess Cruises said.

“The safety and security of guests is the company’s highest priority, and Princess will continue updating impacted guests and travel advisors as more information is available.”

The US-based brand, which owns 24 ships, will also honour travel agent commissions on paid-in-full bookings.

New York-listed Carnival also plans to keep four ships owned by German brand AIDA Cruises away from the Russian port for the upcoming summer season.

The vessels are the 2,050-berth AIDAdiva (built 2007), the 2,686-berth AIDAmar (built 2012), 6,654-berth AIDAnova (built 208) and the 1,266-berth AIDAvita (built 2001).

The brand said the ships will instead call to destinations such as Copenhagen, Oslo, Visby and Riga, Latvia.

“AIDA Cruises observes the dramatic events in Ukraine with great concern,” it said.

“The sympathy and thoughts of all members of the Aida family, which unites employees from a wide range of nations, are with the people in the affected regions.”

New York-listed, Miami-based Norwegian Cruise Line Holdings said on 24 February that it might suspend calls to St Petersburg but plans to keep vessels in the Baltic Sea.

The owner of 28 ships conducts 50 sailings per year in the Baltic region but only 5% of its total capacity visits the Russian city.

Royal Caribbean Group, which is also based in Miami and listed in New York, said it plans to keep visiting St Petersburg for now.

“With the recent events, it is increasingly uncertain whether we can visit St Petersburg, Russia,” it wrote in a letter to passengers.

“At this time, it is our intention to sail to St Petersburg.”