NSA whistleblower Edward Snowden has submitted a request for asylum to a further six countries, bringing the total to 27, WikiLeaks has said.

Julian Assange's whistleblowing organisation said it was not going to name the countries to thwart attempts by US intelligence agencies to hamper the bids.

WikiLeaks tweeted:

Snowden, who remains stuck in legal limbo at Moscow's Sheremetyevo airport where he arrived from Hong Kong without legal travel documents, has been steered by WikiLeaks in his bid to find a safe haven from US prosecutors.

WikiLeaks legal adviser Sarah Harrison delivered requests for asylum on Snowden's behalf to 21 countries, including nine European Union member states, Norway, Iceland, Switzerland, the Brics (Brazil, Russia, India, China), and some Latin American nations at the end of June.

The move has met little success.

The 30-year-old former NSA contractor was rejected outright by Brazil, Finland, Germany, India and Poland. Another eight states said they would consider only asylum applications made on their soil.

Only Venezuela and Bolivia said they were considering the application.

Boliva's warm reception cost President Evo Morales a 13-hour unscheduled stay in Austria after his plane was forced to land in Vienna over claims that Snowden was on board.

Morales' flight from a summit in Moscow was detoured after the captain was denied access to French, Italian, Portuguese and Spanish airspace. The incident triggered a massive diplomatic row, with La Paz claiming that Morales had been kidnapped and later threatening to close the US embassy in response.

Leaks by Snowden have revealed the NSA's sweeping data collection of US phone and Internet records. He is wanted on espionage charges.