President Barack Obama has publicly displayed a relaxed attitude toward Snowden's movements, saying last month that he wouldn't be "scrambling jets to get a 29-year-old hacker."
But WikiLeaks said in a message posted to Twitter on Friday that it would not be identifying the six new countries involved "due to attempted US interference."
The message appeared to be an allusion to the drama surrounding the flight of Bolivian President Evo Morales, whose plane was recently abruptly rerouted to Austria over suspicions Snowden was aboard.
US officials wouldn't directly answer questions about whether they had any information leading them to believe that Snowden was on Morales's plane.
They have said that officials have contacted their counterparts across Europe to remind them that they would like to see Snowden returned to the US.