"We would advise any government that there's only one place he should travel, and that's back here to the US to face the charges he faces,” Marie Harf, a spokeswoman for the State Department, told AFP on Wednesday.
Edward Snowden's Russian lawyer has warned the NSA whistleblower not to travel to Norway to pick up a freedom of expression prize even if he received assurances from the Norwegian government, as the risk of extradition to face spying charges in the US is too great.
Anatolij Kutsjerna told Russia's Echo Moskvy radio station that Norway had an active extradition treaty with the United States, and that the US had warned other governments not to host Snowden.
The Norwegian Academy of Literature and Freedom of Expression on Tuesday awarded Snowden the Bjørnson Prize -- named after a Norwegian Nobel literature laureate -- "for his work protecting privacy and for shining a critical light on US surveillance of its citizens and others."
The academy's president Hege Newth Nouri is pushing Norway's authorities to guarantee Snowden safe passage so that he can come to receive the prize.
She added that the charges against Snowden were "very serious," adding that "if he had the courage of his convictions that he claims, he would come face justice here in the US."
Norwegian Justice Minister Anders Anundsen, from the Progress Party, refused to provide any guarantees to Snowden.
“I will not take over case management for individual cases. This case will be treated on an equal footing with all other cases of the same type,” he said.
Michael Tetzschner, an MP for Norway's Conservative Party, reiterated his previous opinion that Snowden should be arrested and extradited if he steps onto Norwegian soil.
Edward Snowden has been granted a three-year residence permit in Russia, which allows him to leave the country for up to a month without losing his right to return.
Snowden, 31, a former analyst at the US National Security Agency, has lived in exile in Russia since 2013 after revealing mass spying programmes by the United States and its allies.
The US administration has branded him a hacker and a traitor who endangered lives by revealing the extent of the NSA spying program.
The Academy on Monday sent letters requesting assurances from the Norwegian government that Snowden would not be extradited to the US if he travelled to Norway to receive the 100,000 kroner ($12,700, 11,500 euros) prize money in person on September 5.