Bolivia on Monday demanded France, Portugal, Spain and Italy reveal who told them that former US spy agency contractor Edward Snowden was aboard President Evo Morales' flight from Moscow last week.
Bolivia said it was an act of "state terrorism" by the United States and its European allies that the four countries banned Morales' plane from their airspace on suspicions it was carrying the US fugitive to Bolivia in defiance of Washington.
The government in La Paz told the European ambassadors to provide formal explanations on Monday to the foreign ministry.
"We are simply asking the government of Spain and the other governments, of course, to clarify and explain where that version of Mr. Snowden being on the presidential plane came from," communications minister Amanda Davila said. "Who spread that fallacy, that lie?"
Davila said some diplomats already had responded but did not say who.
"As experts in international law and human rights have said, this is a massive attack," she said. "It's the first case of state terrorism against a president, against a nation, against a people. That's what we're talking about now."
Bolivia and other outspoken leftist governments in Venezuela and Nicaragua are the only countries so far that have publicly offered asylum to Snowden, who is believed to be holed up in the transit area of Moscow's Sheremetyevo International Airport, where he landed on June 23 from Hong Kong. The United States has revoked Snowden's passport.
Washington wants him arrested on espionage charges for divulging details of extensive secret surveillance programs. US President Barack Obama has said any countries that give Snowden shelter would face serious costs.
Venezuelan President Nicolas Maduro said on Saturday he had not yet had contact with Snowden and would wait until Monday to see if the former National Security Agency contractor took up the asylum offer. The Bolivian government believes the United States knew that Snowden was not on Morales' plane and simply wanted to intimidate Morales because of his outspoken criticism of US policies.
"We consider that the US knew that Mr. Snowden was not on that plane because there is no way President Morales could leave the Moscow airport without the surveillance and checks that are always done for official flights," Davila said.
On Sunday, Bolivian foreign minister David Choquehuanca said his Spanish counterpart, Jose Manuel Garcia-Margallo, told him during the flight troubles last week that he had been informed that Snowden was on Morales' plane.
According to Choquehuanca, Garcia-Margallo asked the Bolivians for a written note vowing the American was not a passenger before flight permits were restored.