Ecuadorean President Rafael Correa has said US had asked him not to grant asylum for former US spy agency contractor Edward Snowden in a "cordial" telephone conversation with US Vice President Joe Biden.

Mr Correa said he vowed to respect Washington's opinion in evaluating the request.

The Andean nation says it cannot begin processing Snowden's request unless he reaches Ecuador or one of its embassies.

Mr Snowden, who is wanted by the United States for leaking details about US communications surveillance programs, is believed to still be at the Sheremetyevo airport in Moscow after leaving Hong Kong.

Praising Mr Biden's good manners in contrast to "brats" in the US Congress who had threatened to cut Ecuador's trade benefits over the Snowden issue, Mr Correa said during his weekly television broadcast: "He communicated a very courteous request from the United States that we reject the (asylum) request."

Mr Biden initiated the phone call, Mr Correa said.

"When he (Snowden) arrives on Ecuadorean soil, if he arrives ... of course, the first opinions we will seek are those of the United States," Mr Correa said.

A senior White House official travelling with President Barack Obama in Africa on Saturday confirmed the conversation had taken place.

The case has been a major embarrassment for the Obama administration, which is now facing withering criticism around the world for the espionage program known as Prism that Mr Snowden revealed.

A German magazine, citing secret documents, reported today that the US bugged European Union offices and gained access to EU internal computer networks, which will likely add to the furore over US spying efforts.