Whistleblower Edward Snowden, currently promoting a new memoir, has claimed a surge in the use of private contractors by US intelligence agencies, has led to a “creeping authoritarianism”.

Against the backdrop of the whistleblower complaint being examined by Congress that alleges Donald Trump pressured the leader of Ukraine to dig up dirt on Joe Biden, the 36-year-old Mr Snowden said private contractors – as he once was – had very few legal prohibitions on what they could do.

Speaking to Democracy Now from his home in Moscow, where he has spent six years, Mr Snowden said the intelligence agencies faced a cap as to how many members of staff they could take on. The solution, he said, was to hire private contractors who had earned the sufficient security clearance.

“A significant amount, and potentially even a small majority, of the most important work in government, in intelligence, is today performed by contractors, not government employees,” said Mr Snowden, whose book is titled Permanent Record.

“And this is because, in the actual contracting language, there are very, very few tasks that contractors are legally forbidden from doing. And it’s basically, the only things contractors can’t do is press the red button that fires a missile.”

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Mr Snowden, who was employed by NSA contractor Booz Allen Hamilton having previously worked for Dell and the CIA when he in 2013 leaked details of a massive US domestic and foreign surveillance programme, said private contractors were “not supposed to actually commit a crime — something that the government could do, and it wouldn’t be a crime”.

He added: “But everything else — building the system of mass surveillance, installing it, applying it, using it to gather or search through all this information that’s already been collected to build perfect histories of private lives — all of these things are fair game and are done routinely, every day, right now, by people who are not formally government employees. That’s how the system works, and that’s what a contractor is.”

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Mr Snowden expressed sympathy with the whistleblower who has made accusations about Mr Trump’s call to Volodymyr Zelensky, in which he asked him to look into allegations of misconduct by Mr Biden when he was vice president and sought the ousting of a prosecutor probing a company that employed Mr Biden son’s.

He said: “They want to talk about the whistleblower rather than the government’s own wrongdoing.”

Mr Snowden said he believed ordinary people were becoming disenchanted with the major technology firms.

“This shift in the way our systems work is what is creating, I think, fundamentally, the creeping authoritarianism that we see today,” he said.