Bolivia has accused European countries of an "act of aggression" for refusing to allow its presidential jet into their airspace, amid suggestions US fugitive Edward Snowden was on board.
Bolivia said France, Italy, Spain and Portugal had blocked the plane.
President Evo Morales was flying back to Bolivia from Moscow when the plane was forced to stop in Vienna.
Meanwhile, France has urged EU-US trade talks be delayed amid the fallout from secrets leaked by Mr Snowden.
The talks are due to begin on Monday but claims that the US bugged EU diplomatic offices in the US, and spied on internal computer networks, have upset transatlantic relations.
French government spokeswoman Najat Vallaud-Berkacem said the talks should be suspended for 15 days to enable mutual trust to be restored.
However, a spokesman for German Chancellor Angela Merkel said Berlin did not back a delay to the talks, which correspondents say if successful will deliver the biggest trade deal in history.
Once grounded in Vienna, Mr Morales' jet was reportedly searched for Mr Snowden.
He was apparently not on board and is still believed to be in Moscow's Sheremetyevo airport, from where he is reportedly seeking asylum in Bolivia and several other countries.
The incident came hours after Mr Morales said his country would consider a request for political asylum from Mr Snowden.
Bolivia's UN envoy Sacha Llorenti told reporters in Geneva that he would complain to the UN about the European countries' actions.
"The decisions of these countries violated international law. We are already making procedures to denounce this to the UN secretary general," he said.
But France denied refusing the plane permission, and Spain subsequently said its airspace was open to the jet.
Portugal said it had granted permission for the plane to pass through its airspace but denied the plane's request to make a refuelling stop in Lisbon because of unspecified technical reasons.
And an unnamed Vienna official told the Associated Press news agency that Mr Morales had requested permission to land because there was "no clear indication" the plane had enough fuel to continue its flight.
But Mr Llorenti continued to insist that permission to fly through the countries' airspace had been denied at the bidding of the US.
"We have no doubt that it was an order from the White House... For no reason whatsoever should a diplomatic plane with a president [inside] be diverted from its route and forced to land in another country."
Demonstrators marched on the French embassy in La Paz, burning the French flag and demanding the expulsion of the ambassador to Bolivia over the affair, said reports.
Ecuadorean President Rafael Correa asked that the Unasur group of South American nations call an urgent meeting over the matter, Unasur's secretary general said in a statement on Wednesday.
The secretary general of the Organization of American States (OAS), Jose Miguel Insulza, expressed his "deep displeasure" with the "lack of respect" allegedly shown by the countries that denied airspace to Mr Morales' jet.
'Kidnapping' of president
And Bolivia's Vice-President Alvaro Garcia said a group of Latin American leaders would meet in Cochabamba, Bolivia, on Thursday to discuss the case.
Austrian officials said the airport authorities had searched the plane, but with Mr Morales's permission.
The plane took off from Vienna on Wednesday morning, having landed there late on Tuesday. It is now on its return journey to Bolivia.
Mr Morales said presidents should have the right to travel anywhere in the world.
"It's not an offence against the president, it is an offence against the country, against the whole of the Latin American region," he said before taking off.
He described the incident as "almost a kidnapping of 13 hours".
However, Eurocontrol - which co-ordinates Europe's airspace and traffic control - said it was "a national decision whether or not to accept a state flight" under the terms of the Chicago Convention on International Civil Aviation.
Mr Snowden is wanted by the US on charges of leaking secrets he gathered while working as a contractor for the National Security Agency (NSA), America's electronic spying agency.