How will newest allegations of NSA spying in Mexico affect bilateral ties?

Mexico warned the United States on Tuesday that its reported surveillance of top Mexican officials could sour security cooperation between the countries, and it demanded to know what measures the Obama administration is taking to prevent further spying on its leaders.

The statement was Mexico’s angriest yet in response to revelations about surveillance by the National Security Agency that also have roiled Brazil and France.

Mexico said it had tightened governmental cyber-security, the latest sign that the scandal over leaked NSA documents is stirring nations that are considered close US allies to build more vigorous digital-security barriers.

Foreign Secretary Jose Antonio Meade, reading a statement in Geneva, lambasted the alleged NSA penetration of email accounts belonging to President Enrique Peña Nieto and former President Felipe Calderón. The reports, which came out in the German news outlet Der Spiegel, were based on documents leaked by former NSA contractor Edward Snowden, who’s in exile in Moscow.

Mr. Meade noted that Obama had promised President Peña Nieto in a telephone call Sept. 5 that the US government would offer an explanation of the allegations. Obama reiterated that pledge at the Group of 20 summit days later in St. Petersburg, Russia, Meade said.

But US explanations were “insufficient and thus inadmissible,” he said, and the time for explanations has ended. He demanded “expedited corrective measures” so that “activities of this type do not occur.”

Displaying anger and pique, Meade said Mexico had worked closely with the United States on issues of security and counterterrorism.

“Shared security within a neighborhood that is respectful and jointly responsible cannot be built by breaking the law and violating the trust,” Meade said.

“Mexico is convinced that such espionage constitutes a violation of the standard, an abuse of trust built between partner countries, and dishonors the historic friendship between our nations.”

Speaking in Mexico City, Interior Secretary Miguel Angel Osorio Chong said the Peña Nieto administration was investigating whether any Mexican officials, either intentionally or by negligence, had aided in the reported NSA surveillance.

Mr. Osorio Chong said officials had “reinforced the security mechanisms of voice and data communications and networks, software and coding systems and encryption used by the president and all government security areas.”

The Der Spiegel report cited a “top secret” NSA report from an operation code-named “Flatliquid” that “exploited a key mail server in the Mexican Presidencia domain within the Mexican presidential network to gain first-ever access to President Felipe Calderón’s public email account.”

It said the achievement would help US analysts gauge “internal stability” in Mexico. An NSA document previously leaked to Brazil’s O Globo newspaper said US analysts had broken into then President-elect Peña Nieto’s email to determine whom his Cabinet picks would be.

Brazilian President Dilma Rousseff in September canceled a state visit to Washington that had been slated for this month, and she asked legislators in her country to require US technology companies to store private user data on Brazilian-based servers.

France is also upset by revelations of US espionage. The newspaper Le Monde reported Monday that the NSA had swept up 70.3 million telephone calls and text messages of businesses and individuals in France in one 30-day period.

Le Monde and Der Spiegel have gained access to NSA documents leaked by Mr. Snowden, who was granted temporary asylum in Moscow by Russian President Vladimir Putin.

On Monday, former President Calderón, who’s a guest scholar at Harvard’s Kennedy School of Government, tweeted that the reports of NSA surveillance were “an affront to the country’s institutions since they were made during my tenure as president of the Republic.” Calderón governed until last Nov. 30.