The apparent diversion of the Bolivian president's airplane in Europe has fed suspicion that the United States is quietly orchestrating an international manhunt for former NSA contractor Edward Snowden despite efforts by President Barack Obama to downplay the magnitude of that pursuit.

The circumstances surrounding the unscheduled landing of Bolivian President Evo Morales's aircraft in Vienna remained murky on Wednesday, with U.S. officials refusing to comment on Bolivian claims that the flight was blocked as part of an effort to ascertain whether Snowden - who has acknowledged leaking classified U.S. intelligence documents - was on board.

Bolivian authorities accused the United States of forcing Morales' plane to land in Austria by putting pressure on American allies including France and Portugal, and possibly Spain and Italy, to refuse to allow the Bolivian leader's plane to enter their airspace.

Those governments have so far not acknowledged blocking Morales' path at the behest of the United States. But their opaque statements, and a search of the aircraft by Austrian authorities, suggests that at least some U.S. allies in Europe have been persuaded to assist in the pursuit of Snowden even while expressing anger over revelations that their citizens and officials have been swept up in the surveillance programs that Snowden exposed.

Snowden, who has been charged with stealing and disclosing classified materials, is believed to still be in Moscow.

Escalating protests

Morales was allowed to resume his return to La Paz on Wednesday, but his forced overnight stay in Vienna ended amid escalating protests from Bolivian officials.

They were joined by leaders across a range of leftist countries in Latin America who characterized the redirection of Morales's presidential plane as an affront that put his life in jeopardy and underscored vestiges of European colonialism and racism toward Latin America. Morales is an Aymara Indian, the first to be elected president in Bolivia's modern history.

"What has happened is EXTREMELY grave," Ecuador's president, Rafael Correa, wrote via Twitter. "Latin America demands reactions and explanations."

The 12-member Union of South American countries called an urgent meeting of the region's presidents today in Cochabama, Bolivia, to determine what course of action could be taken against both Washington and the European countries accused of having blocked Morales' flight path. At the United Nations, Bolivia's ambassador, Sacha Sergio Llorentty Soliz, has "raised a ruckus" in a series of phone conversations with U.N. Secretary General Ban Ki-moon's top aides, according to a senior U.N.-based official.

The highly unusual detour of a head of state's flight came just days after Obama seemed to signal that the United States would avoid extraordinary measures beyond seeking Snowden's extradition. "I'm not going to be scrambling jets to get a 29-year-old hacker," Obama said during a visit to Senegal last week.

It also pointed to a possible intelligence blunder. Still, former U.S. officials said that if the United States were involved, it may reflect a calculation by the Obama administration that the risk of embarrassment from an unsuccessful search was more than offset by a desire to avoid seeing Snowden arrive to a hero's welcome in La Paz.

Before departing Moscow, Morales had suggested his country would be willing to consider granting Snowden asylum, a remark that triggered speculation that the Bolivian president might head home with the former NSA contractor in tow.

For that reason, former Director of National Intelligence Dennis Blair said, U.S. intelligence officials would likely have been asked not whether they could be certain Snowden was on the aircraft, but whether they could assure the White House that he was not.

The calculation would weigh "the downside of requesting closing the airspace versus the possible damage of what if (Snowden) got to Bolivia," said Blair, who noted that he did not have firsthand knowledge of the matter.

Paddling furiously

Referring to Obama's recent comments on Snowden, Blair said that the administration may be seeking "to try to downplay it from a public point of view," but that it is clear the effort to apprehend Snowden has not waned. "Below the water, the feet of the duck are paddling furiously."

The exposure of that effort in the search of the Bolivian aircraft may complicate Snowden's efforts to seek asylum as well as the U.S. pursuit of him. Former officials said Snowden, who turned 30 last month, will likely be increasingly wary of leaving Moscow, where he has been held out of public view since fleeing Hong Kong last month.

European officials have offered varying accounts of their involvement in the diversion of Morales's plane. The French government acknowledged a "delay in the granting the president's plane permissions to fly over French territory," adding that authorization was given as soon as authorities were informed that the aircraft in question was Morales's.

Spanish and Portuguese officials claimed that they had not withheld overflight permission, contradicting Bolivia's claims. Italian authorities had not yet commented on the matter, according to press reports Wednesday.

The diversion appears to have been enabled by the Bolivian aircraft's search for a location where it could refuel before departing again toward La Paz. The plane's recorded flight path traced a straight southwest line across Austria before making a sudden U-turn.

Austrian officials said the aircraft was searched by border police after Morales gave permission, according to an Associated Press report. Bolivian and Austrian officials both said that Snowden was not on the plane.