John Kerry tells Snowden to 'man up and come back to US'

Whistleblower Edward Snowden has told NBC News he is "comfortable" with his actions in revealing details of the US National Security Agency's surveillance programme.

However Snowden, who is now living in exile in Russia, admitted he does feel a "sense of loss" at not being able to return to the US.

Read: Edward Snowden in TV interview: I want to go home

US Secretary of State John Kerry invited Snowden to "man up and come back to the United States."

"The bottom line is this is a man who has betrayed his country, who is sitting in Russia, an authoritarian country where he has taken refuge," Kerry told the CBS network.

"If he has a complaint about what's the matter with American surveillance, come back here and stand in our system of justice and make his case," Kerry said.

"There have been times throughout American history where what is right is not the same as what is legal," Edward Snowden told NBC News.

Former US spy agency contractor Edward Snowden has told a US television interviewer he would like to go home from asylum in Moscow, but that if necessary he would seek to extend his stay in Russia.

US officials said he was welcome to return to the United States if he wanted to face justice for leaking details of massive US intelligence-gathering programmes.

"If I could go anywhere in the world, that place would be home," Snowden told NBC Nightly News anchor Brian Williams in an excerpt from the interview that aired on Wednesday.