(Editor's Note: Updated Jan. 5, 4:00 a.m. EST) -- Two more cruise ships -- Seabourn Sojourn and Star Princess -- have been targeted by Argentine protesters in Buenos Aires. Union Jack flags and tyres were burnt, and passengers -- many British and elderly -- were intimidated as they tried to leave the ships. The latest protests were sparked by the ongoing dispute over cruise ship calls to the Falkland Islands, and come just days after Argentine Prime Minister Christina Kirchner wrote an open letter to David Cameron asking for the islands to be returned to Argentina. In December Regent Seven Seas' Seven Seas Mariner and Oceania Regatta both cancelled Falkland Islands visits in early February due to the ongoing unrest.

(11:00 a.m. EST) -- A cruise ship headed for the Falkland Islands has again become a focal point of international tension between the U.K. and Argentina.

Seabourn Sojourn -- a Bahamas-flagged luxury ship sailing under the umbrella of American-owned Carnival Corporation -- was delayed while trying to leave the port of Buenos Aires, Argentina on 4 December. The reason behind the delay remains unclear, however.

A statement from Seabourn said the ship's departure was postponed "due to the temporary unavailability of a required tugboat escort." But reports from a number of British media outlets have ascribed responsibility for the delay to a protest by Argentine port workers.

Reportedly, workers under the direction of United Maritime Workers Union bosses, held the ship in port for seven hours, demanding that Sojourn's captain pledge not to visit the Falkland Islands. Eventually, the 450-passenger ship was allowed to depart, continuing on to Montevideo, Uruguay, on its 15-night South America cruise. The ship will make its scheduled call at Port Stanley in the Falkland Islands, on 8 December, according to Seabourn.

Other Cruise Ships Affected

Diplomatic tensions between Argentina and Britain have been running high this year -- the 30th anniversary of 1982's Falklands War -- and a number of cruise ships have been affected. Last week, AIDAcara cancelled a stop in Port Stanley following protests in Buenos Aires which culminated in an attack on the offices of the Argentine Shipping Services.

During the raid, attackers told shipping agents that they would prevent cruise ships from berthing in Argentine ports unless trips to the Falklands were removed from itineraries, according to Britain's Daily Telegraph. Reportedly, no police intervened and no arrests were made following the incident.

Subsequently, the British government formally summoned the Argentine ambassador to the Foreign Office in London to lodge diplomatic complaints against what a British official told Reuters may have been a state-approved attack.

A Foreign Commonwealth Office spokesperson told Cruise Critic that the Ambassador was summoned "over the Government of Argentina's failure to respond to several requests for an assurance that British and other shipping would not be disrupted in Argentine ports.

"Ships engaged in legitimate commercial business, including tourism, should not be prevented from going about their business," the statement continued. "The Argentine government's increasingly aggressive actions against the people of the Falklands Islands are unacceptable and must stop."

The U.K. is expected to file claims against Argentina before the International Maritime Organization, the European Union (and by extension the World Trade Organization).

At least three other ships have been affected by the diplomatic row this year. In February, P&O Cruises's Adonia and Princess Cruises' Star Princess were both refused entry to the Argentinian port of Ushuaia, because they had visited the Falklands.

Affects to the Falkland Islands

Cruise ship stops are estimated to be worth at least £10 million to the islands; a sizable revenue stream that, if disrupted, would take a toll on the Falklands' economy.

The Falklands Government has issued a strongly-worded statement condemning the "intimidation of cruise operators," and calling on cruise lines to "stand firm" in their commitment to visit the islands. The statement accused Argentina of "attempting to bully and threaten our three thousand people and strangle the economy," pointing out that there are "countless families in the Islands whose livelihoods depend on the cruise vessel industry."

Disruption to shipping in the region is tied to the Gaucho Rivero Bill, a provincial law voted by the local legislatures from the provinces of Tierra del Fuego, Santa Cruz, Chubut, Rio Negro and Buenos Aires. The legislation -- impeding access to the ports of these provinces -- refers mainly to British or convenience-flagged vessels involved in the Falklands' hydrocarbons industry, but local unions, politicians and other groups have extended the interpretation to include cruise ships, according to the South Atlantic News Agency.

A referendum addressing the Falklands' sovereignty is scheduled for March 2013, in which the 3,000 island residents are expected to reject Argentine efforts to claim ownership -- and support British rule -- over the disputed archipelago.

--by Jamey Bergman, U.K. Production Editor