South American leaders defended their right to offer asylum, venting anger at claims of US spying in the region while intelligence leaker Edward Snowden's fate hangs in the balance.
Washington wants Snowden, currently in limbo in Moscow, arrested for disclosing details of the massive US electronic intelligence operations around the world.
Venezuela, Bolivia and Nicaragua -- all run by leftist governments -- have offered Snowden asylum. The 30-year-old US fugitive however told rights activists in Moscow on Friday that he would seek interim refuge in Russia.
Four European countries also came under attack in Montevideo at a summit of Mercosur, the regional bloc, for shutting off their airspace and holding up a plane carrying Bolivian President Evo Morales, apparently on suspicion that Snowden was aboard.
Venezuelan President Nicolas Maduro also called for stronger regional cyber-security after documents leaked by Snowden, a former National Security Agency (NSA) contractor, allegedly show that Washington has engaged in a mass of electronic spying in several Latin American countries.
The Mercosur leaders issued a statement reaffirming "the inalienable right of every state to grant asylum," a right which, they said, "must not be restricted or curbed".
"It is fundamental to ensure that the right of asylum seekers to travel safely to the country granting asylum be guaranteed," they added, in a thinly veiled reference to US pressure to block Snowden's possible departure from Russia to Venezuela.
The South American leaders rejected "any attempt at pressure, harassment or criminalization by a state or third parties" in response to a decision to grant asylum.
They demanded "an immediate end to such practices and explanations as to their motivation and their consequences."
They also plan to push for the adoption of Internet regulatory rules, with an emphasis on cyber-security "to guarantee the protection of communications and preserve the sovereignty of states."
Snowden has been stranded at Moscow's Sheremetyevo Airport since arriving on a flight from Hong Kong on June 23. His US passport has since been revoked.
Mercosur leaders also said they would recall their ambassadors from Spain, France, Italy and Portugal for consultations in protest at the four nations' decisions to close their airspace to the plane carrying Morales last week.
Brazilian President Dilma Rousseff, whose country was reportedly a key target for US electronic surveillance, slammed NSA activities disclosed by the O Globo newspaper.
It is time for Mercosur "to set a limit... We must adopt pertinent measures to avoid a repetition of such situations," she said.
Argentine Foreign Minister Hector Timerman told the summit that more than 100 of his country's officials were under electronic surveillance from a nation he did not name.
"I received less than an hour ago from a country present in this room the names (of the targeted officials) with their emails and passwords," he said.
And Argentine President Cristina Kirchner said Morales' airplane holdup raised fears that her presidential plane could be impounded over a debt dispute.
"If I am aboard, I don't know if they won't seize me as well," she said. "There are new forms of colonialism, more subtle than those practiced centuries ago."
In January, the Argentine government had to rent a British aircraft for Kirchner's trip to Cuba, the United Arab Emirates, Indonesia and Vietnam for fear that her official plane would be impounded in a debt dispute.
Last year, a court in Ghana impounded the Argentine navy sail ship Libertad for two months following a request from a Cayman Islands-based investment firm that said Buenos Aires owed it $370 million.
Argentina, Brazil and Uruguay suspended Paraguay from Mercosur after Paraguay's Congress impeached leftist president Fernando Lugo and removed from office in June 2012. The four countries are the founding Mercosur members.
With Paraguay gone, Argentina, Brazil and Uruguay admitted leftist Venezuela as a Mercosur member.
On Friday the bloc agreed to reinstate Paraguay's membership once rightwing tycoon Horacio Cartes, elected president in April, takes office on August 15. Cartes however appeared to reject the offer.
Timerman said that Paraguay's readmission "implies accepting" Venezuela's admission to the group -- a move president-elect Cartes said in a statement did not follow the proper legal procedure.
Further complicating the issue, Venezuela's Maduro took over the trade bloc's rotating presidency Friday from Uruguay's president Jose Mujica.