The US Government threatened to starve Berlin of intelligence if it harboured fugitive document-leaker Edward Snowden, German Vice Chancellor Sigmar Gabriel says.

The National Security Agency (NSA) leaker considered Germany as a place of refuge after he fled to Russia from the United States via Hong Kong in 2013.

Moscow granted Snowden a three-year residency permit in the country, which expires in August 2017. At that date Snowden will need to apply for citizenship or move elsewhere.

In a speech given this week in Hamburg Gabriel said Washington would withhold information on "plots" and "intelligence matters" if Germany offered Snowden asylum.

“They told us they would stop notifying us of plots and other intelligence matters,” Gabriel said, according to an Intercept report.

The report did not name the US agency or official who made the extraordinary threats. Severing intelligence which appear to place the country of 80 million at heightened risk of terrorist and espionage attacks.

Germany would be obligated to extradite Snowden to the US if he entered the country, Gabriel says, and faced being cut-off from "all intercepted intelligence sharing" if it offered asylum, according to the report.

Questions of whether Snowden should be granted asylum in Germany were raised in November 2013 when the leaker was still under temporary protection from Moscow.

German Green Party figure Hans-Christian Ströbele who was the first parliamentarian to visit the leaker during his Moscow exile raised the concept after the US had submitted an extradition request for Snowden should he have set foot in the country.

Vice Chancellor Gabriel said it was "a shame" Snowden was confined to “Vladimir Putin’s autocratic Russia”.

The report comes as Snowden's Russian lawyer Anatoly Kucherena said last month the former sys-admin is reportedly ready to return to the US if he is promised a fair trial. ®