The Adonia, owned by P&O cruises, and the Princess Cruises vessel Star Princess were both blocked from entering Ushuaia in southern Argentina after both ships stopped at the Falklands on Saturday.
“We are very concerned to hear the Adonia and Star Princess have been refused access to the port of Ushuaia,” a spokesman for Britain’s Foreign Office said in London.
“There can be no justification for interference in free and legitimate commerce.
“British diplomats in Argentina are urgently seeking to clarify the circumstances surrounding this incident, and we are in contact with the company concerned.”
Tensions are running high between Britain and Argentina over the Falklands, which London controls but Buenos Aires claims, ahead of the 30th anniversary in April of the start of the war between the two nations over the South Atlantic islands.
Argentina has also reacted angrily to the deployment of Prince William to the Falklands as part of his job as a Royal Air Force search and rescue pilot, and to a planned fact-finding trip by British lawmakers next month.
The Argentine province of Tierra del Fuego said they “applied the law” in denying port access to the Carnival Corporation ships the Star Princess and the Adonia.
“The Governor of Tierra del Fuego, Antarctica and the South Atlantic Islands, Fabiana Rios, decided not to allow the docking in the port of Ushuaia (3,200 km south of Buenos Aires)” of the two ships, Tierra del Fuego authorities said in a statement.
“We’ve never had a ship stopped from coming into an Argentine port before,” Julie Benson, spokeswoman for Carnival affiliate Princess Cruises, told AFP.
Carnival UK, which owns both P&O and Princess Cruises, said in a statement the Adonia was now sailing towards Punta Arenas in Chile, its next port of call on an 87-night tour of South America.
The Star Princess was on a 14-night South America cruise which started in Rio de Janeiro on February 18.
The Falklands, located off the southern coast of Argentina, have been under British control since 1833.
A brief 74-day war in 1982 cost the lives of 649 Argentine troops, 255 British troops and three Falkland Islanders, with Britain retaining control.
The United Nations has called on Britain to start talk on decolonization, but London has refused to do so.