Fugitive US intelligence leaker Edward Snowden was staring at the logistical nightmare of escaping Russia for a safe haven in Latin America on Sunday after three leftist leaders offered him asylum in their states.

Bolivia on Saturday became the third country to extend an offer of asylum to the 30-year-old former US National Security Agency (NSA) contractor sanctuary after similar guarantees from Venezuela and Nicaragua.

All three nations have strained ties with Washington and represent Snowden's best options after his rejection by most of the 21 nations he had applied to for protection last week.

The fugitive himself remained hidden out of sight in a Moscow airport transit zone for the 15th day on Sunday after arriving there upon spilling his US surveillance secrets in Hong Kong.

But Snowden was back in the press Sunday, claiming that the NSA operates broad secret spying partnerships with other Western governments who are now complaining about its programmes.

In comments made before his exposure of Us espionage practices, Snowden told German news weekly Der Spiegel that NSA spies are "in bed together with the Germans and most other Western states".

Washington has urged Russia to hand over Snowden as a gesture of good will because the two sides have no extradition agreement.

President Vladimir Putin -- a former KGB spy who has often sparred with the White House during his 13 years in power -- has flatly refused and suggested that Snowden had better quickly decide himself where he wanted to go.

But Snowden's options at Moscow's Sheremetyevo airport are limited because the only flights to Latin America are routed through Cuba -- a country that has remained conspicuously silent throughout the dispute.

Snowden also faces the risk of his plane being grounded by a European country as happened to Bolivian President Evo Morales when he was suspected of trying to smuggle the American from Moscow earlier this week.

The mercurial Bolivian leader said that incident had convinced him his country had nothing left to lose by irritating Washington.

Morales declared that Bolivia had "no fear" of either Washington and its European allies.

Bolivia will "give asylum to the American, if he asks", said Morales.

Bolivia was one of 21 countries to which Snowden had applied within the past week, according to the WikiLeaks anti-secrecy website.

Two others included Venezuela and Nicaragua -- nations that also spelled out their intentions over the weekend.

Maduro said on Saturday that "as head of state of the Bolivarian republic of Venezuela, I have decided to offer humanitarian asylum to the young Snowden".

Nicaragua's Daniel Ortega voiced a slightly more toned down message only minutes earlier that same day.

"We are open, respectful of the right to asylum, and it is clear that if circumstances permit it, we would receive Snowden with pleasure and give him asylum here in Nicaragua," Ortega said at a public event.

But Venezuela's foreign ministry made clear on Saturday that it had not made any contact with Snowden since Maduro's invitation.

That makes it uncertain just how much currency a verbal commitment has with Russian authorities who are seeking clear documented evidence of Snowden having a legal future destination point.

Snowden never boarded his plane out of Moscow for Cuba on June 24 for unexplained reasons.

But analyst said it was likely that he was simply not allowed to board by the Russians because he had no valid transit papers after his US travel passport had been revoked.

Neither do countries such as Bolivia and Venezuela have consular sections in Sheremetyevo that could issue Snowden with the required papers.

The possibility of the American leaving Moscow with a foreign delegation meanwhile is also slim given that dignitaries all fly to and from a separate airport called Vnukovo on the other side of Moscow to which Snowden has no access.

Even the possibility of Moscow diplomats from Venezuela or some other country handing Snowden his travel papers at Sheremetyevo would not resolve all his problems.

Morales' plane was grounded in Vienna on Tuesday because several EU states suspected that he was smuggling Snowden out of Moscow after paying a visit there for a gas summit.

But all the flights to Cuba pass through the same EU air space and there is no guarantee that Snowden's jet would not be stopped and searched.

Cuba itself has preferred to stay out of the conflict and has issued no indication of being willing to receive the American fugitive at its Havana airport.

"He's dead, in a figurative sense," said French espionage historian Sebastien Laurent.

"Given the seriousness of what he has done, he will never find a safe haven."