BUENOS AIRES (REUTERS) - Latin American leaders slammed European governments for diverting Bolivian President Evo Morales' plane on rumours it was carrying a wanted former US spy agency contractor, and announced an emergency summit in a new diplomatic twist to the Edward Snowden saga.

Bolivia said Mr Morales was returning from Moscow on Tuesday when France and Portugal abruptly banned his plane from entering their airspace due to suspicions that Snowden, wanted by Washington for leaking secrets, was onboard. Italy and Spain also banned the plane from their skies, it said.

The unusual treatment of the Bolivian military aircraft touched a sensitive nerve in the region, which has a history of US-backed coups. Regional leaders, particularly from the left, rallied behind Mr Morales, Bolivia's first indigenous president and a former union leader of the country's coca farmers.

"(These are) vestiges of a colonialism that we thought were long over. We believe this constitutes not only the humiliation of a sister nation but of all South America," Argentine President Cristina Kirchner said in a speech in Buenos Aires.

Heads of state in the 12-nation South American bloc Unasur denounced the "unfriendly and unjustifiable acts." The grouping issued a statement late on Wednesday saying the presidents of Ecuador, Bolivia, Venezuela, Argentina, Uruguay and Surinam had agreed to attend a summit in Cochabamba, Bolivia, on Thursday.

"Latin America demands an explanation," tweeted Ecuadorean leader Rafael Correa. "If what happened to Evo does not merit a Unasur summit, I don't know what does."

Ms Dilma Rousseff, president of regional economic powerhouse Brazil, issued a statement repudiating the European countries that denied Mr Morales access to their airspace based on what she called the "fanciful" notion that Snowden might be on board.

The Chilean Foreign Ministry issued a statement saying it "lamented" what happened to Morales and that more clarity was needed on the facts.

Much more blunt was the statement from Mexico's Congress condemning what it called the "disgraceful and discriminatory"treatment Morales had received in Europe.

A spokesman at France's Foreign Ministry blamed the flap on "an administrative mishap," saying France never intended to ban Mr Morales from its airspace and that there were delays in getting confirmation that the plane had fly-over permits.

International agreements allow civilian airplanes to overfly countries without obtaining permission ahead of every flight.

But state aircraft including Air Force One, the plane that carries the U.S. president, must obtain clearance before they cross into foreign territory.

Government aircraft, whether carrying diplomats or missiles, always require approval before they can enter foreign airspace, legal experts said.

"Every state on the basis of state sovereignty has the right to deny overflight to state aircraft," said John Mulligan, a research fellow at the International Aviation Law Institute at DePaul University in Chicago.

Bolivian officials were quick on Tuesday to accuse the United States of strong-arming the Europeans into denying access to their air space in an "act of intimidation" against Mr Morales for suggesting that while attending an energy conference in Moscow he would consider granting asylum to Snowden if requested. Mr Morales said earlier this week no request had been made.

The White House declined to comment on the assertion that it was behind the plane scandal.
President Barack Obama has warned that giving Snowden asylum would carry serious costs.
Morales was expected back in Bolivia on Wednesday night.

Snowden is believed to be still in the transit area of a Moscow airport, where he has been trying since June 23 to find a country that will offer him refuge from prosecution in the United States on espionage charges.

The Bolivian government said it had filed a formal complaint with the United Nations and was studying other legal avenues to prove its rights had been violated under international law.
Mr Morales has yet to restore full diplomatic relations with the United States after expelling the US ambassador in 2008.

In May of this year, Mr Morales expelled a US development agency from Bolivia in protest after US Secretary of State John Kerry referred to Latin America as Washington's "backyard." The comment was a stark reminder of the United States' history exploiting South America's natural resources and supporting some repressive right-wing governments.

This week's diplomatic mess was bad news for American expatriates planning to celebrate the Fourth of July at the US Embassy in La Paz. The embassy said late on Wednesday that its Independence Day party had been put off "until further notice."