Latin American leaders have resolved to summon the European ambassadors for countries who blocked their airspace to Bolivian President Evo Morales and demand an explanation.
Brazil, Argentina, Uruguay and Venezuela, on Friday decided to call their representatives in Spain, France, Italy and Portugal for consultations.
Bolivia demanded apologies from the four European nations for the July 2, when Morales' plane was blocked from entering the airspace above several countries when the president was flying home from a meeting of natural gas producers in Moscow.
European governments are believed to have acted on suspicions that fugitive US intelligence leaker Edward Snowden, who had been in diplomatic limbo in the Moscow airport, was on board the plane.
The decision to take this stance was made during a summit of the Mercosur trade bloc.
Bolivia, already an associate member of Mercosur, is in the process of becoming a full member of the bloc.
"We emphatically reject the interception of telecommunications and espionage actions in our nations, as they constitute a violation of human rights, of the right of our citizens to privacy and information,'' Mercosur leaders said in the summit's final statement.
"It's unacceptable behaviour that breaches our sovereignty and harms relations between nations."
The South American group also defended the right of asylum after Venezuela, Bolivia and Nicaragua recently offered it to Snowden.
Washington has put pressure on regional presidents to block Snowden from finding refuge in Latin America.
"We repudiate any activity that could undermine the authority of States to grant and fully implement the right of asylum," the statement said.
"We reject any attempt in pressuring, harassment or criminalisation of a State over a country's sovereign right to grant asylum."
'Discriminatory and arbitrary'
Uruguayan Foreign Minister Luis Almagro said the four Mercosur trace bloc nations will recall their own ambassadors in the European countries involved for consultations over the incident.
The actions of the four European countries were "unfounded, discriminatory and arbitrary, in a flagrant violation of the precepts of international law," Almagro said.
He said the summit found that Morales was subjected to "neo-colonial practices."
"It is an incredible, unfriendly and hostile action that violates human rights and affects the freedom of transit and movement and the immunity that every head of state enjoys," Mercosur leaders concluded, according to Almagro.
Brazilian President Dilma Rousseff said that the European actions were offensive to each of the leaders at the summit as Latin American presidents, and vowed "concrete and effective actions, be it with regard to the governments or the ambassadors of those countries."
Rousseff noted media reports based on US National Security Agency (NSA) documents leaked by Snowden that the United States spied on many countries around the world including Mercosur members Brazil, Argentina and Venezuela.