Whistleblower Edward Snowden says he has been working harder and doing more significant things while in exile in Russia than he did while being a contractor for the National Security Agency (NSA).

“The fact is I was getting paid an extraordinary amount of money for very little work [at the NSA] with very little in the way of qualifications,” Snowden said via satellite link during an event at Stanford University on Friday.

In Russia, “that's changed significantly,” the former NSA contractor, who revealed the agency’s vast and controversial surveillance activities in the US and abroad, said.

“I have to work a lot harder to do the same thing. The difference is that, even though I've lost a lot, I have a tremendous sense of satisfaction,” the whistleblower said, as cited by Business Insider.

However, he did not reveal exactly what he has been working on, saying that he is the type of person who believes in being judged on the final result.

Snowden also addressed the ethics of whistleblowing, reminding his audience that he never published a single document himself, but always worked alongside journalists.

The involvement of reporters also allowed the employment of a system of checks and balances while making the revelations, he said.

According to the whistleblower, there was no way for him to leak the files to the press anonymously as it could have led to a witch-hunt within the NSA, putting his former colleagues under threat.

“Whistleblowers are elected by circumstance. Nobody self-nominates to be a whistleblower because it’s so painful. Your lives are destroyed whether you are right or wrong. This is not something people sign up for,” he stressed.

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Snowden added that he is neither a hero nor a traitor, but only a man, who reached a critical moment, after which he just couldn’t remain silent.

“We all have a limit of injustice, of incivility, of inhumanity in our daily life that we can kind of accept and ignore. We turn our eyes away from the beggar on the street. We also have a breaking point and when people find that, they act,” he explained.

“You have to have a greater commitment to justice than a fear of the law,” Snowden added.

The comments came a week after a US federal appeals court ruled that the NSA’s bulk collection of American citizens’ telephone records was illegal.

In a unanimous decision, the Second Circuit Court of Appeals in New York called the bulk phone records collection "unprecedented and unwarranted."

The ruling, which Snowden described as “extraordinarily encouraging,” comes as Congress confronts a June 1 deadline to renew a section of the Patriot Act that allows the NSA’s bulk data surveillance.