Buenos Aires, Argentina ? Despite frequent Latin American summits pledging regional solidarity and ambitious integration plans, the swine flu crisis has opened up a serious rift in Latin American relations.

Angry Mexican officials have issued unusually harsh protests against the decisions by Cuba, Argentina, Ecuador and Peru to suspend direct flights from Mexico despite World Health Organization warnings that such measures are unwarranted.

How can one explain that Latin American countries with relatively little traffic with Mexico suspended direct flights from Mexico, when the United States — which shares a 2,000-mile-long border with Mexico that is crossed by the bulk of the more than 20 million people visiting Mexico annually — has not done so? Mexican officials ask.

While the U.S. government issued a travel alert April 27 recommending that Americans avoid nonessential travel to Mexico, the Obama administration did not suspend flights to and from Mexico. By comparison, countries such as Cuba and Argentina suspended all Mexican flights, and took extraordinary safeguards with Mexicans or recent visitors to Mexico arriving from third countries.

When I arrived at Buenos Aires international airport last Saturday, it felt like being in a country at risk of a health catastrophe. Before leaving the plane, all passengers had to fill out a form asking which countries we had visited over the past 10 days, and to check whether we had any of a list of flu-related symptoms.

Outside the plane, a health official — who, like all other airport employees, was wearing a mask — took the forms, and interrogated each passenger, as a camera filmed the scene. Noting that I had marked symptoms of “coughing” and “running nose,” the official asked me if I had had fever. I said no and was allowed to move on.

Mexican President Felipe Calderon earlier this week protested the “vexing or discriminatory measures undertaken by several countries against Mexico, while other Mexican officials protested Argentina’s high-drama decision to send a plane to Mexico to airlift 218 stranded Argentines.

Among other things, Mexican officials note that while Argentina allows travelers from Mexico to arrive here by American Airlines, Lan Chile or Copa with stopovers in Miami, Santiago de Chile or Panama, respectively, the Argentine government has suspended direct flights by Aeromexico or Mexicana.

“It doesn’t make sense,” Mexican Consul Juan Miguel Ponce told me. “First, the World Health Organization has said that the flow of international travelers does not prevent contagion. Second, allowing passengers to come from Mexico via third countries is hard to explain, because it’s the same passengers.”

Why has Argentina gone overboard with its measures to prevent H1N1 transmission to this country?

The most common answer pointed to by virtually all Argentine newspapers: politics.

Argentina is about to hold crucial June 28 legislative elections, in which President Cristina Fernandez de Kirchner and her husband, former President Nestor Kirchner, are likely to lose a majority in Congress.

According to Argentine press reports, the former president — who still calls the shots — personally gave the order to suspend the flights from Mexico, because he did not want to risk criticism over lax public health standards in the height of the electoral season. The government has been under fire in recent months for an outbreak of dengue fever, a disease that usually spreads in poverty-stricken areas and was thought to be largely defeated in this country.

Some critics, noting that the government is installing a state-of-the-art mobile hospital at the Ezeiza airport, say the president is likely to inaugurate it later this week, and speculate that it may have wanted to maintain the H1N1 crisis alive for maximum exposure in the media.

Argentine officials say the extraordinary measures were taken to protect the population, and that the government has asked its embassy in Mexico for a full report on the situation to evaluate whether to lift the ban on direct flights from Mexico.

My opinion: The governments of Argentina, Cuba, Ecuador and Peru have overreacted. Interestingly, several of these governments are the first to lash out against the United States and to present themselves as champions of Latin American solidarity in international fora.

But when Mexico was facing trouble, the first thing they did was to turn their backs on that country — while Washington stood by its neighbor.