Russia likely interfered in last year’s U.S presidential election, according to former intelligence contractor Edward Snowden, but the American public deserves to see evidence of its involvement, he said in an interview published Wednesday.

“Everybody is currently pointing at the Russians,” Mr. Snowden, 33, told Germany’s Der Spiegel. “They probably did hack the systems of Hillary Clinton’s Democratic Party, but we should have proof of that.”

The U.S. Office of the Director of National Intelligence has concluded that Russia interfered in last year’s election race by using state-sponsored hackers and propagandists to target Mrs. Clinton’s campaign in an effort to hurt her odds of winning the White House.

Officials have blamed Kremlin-tied cybercriminals with security breaches suffered by the likes of the Democratic National Committee and Mrs. Clinton’s former campaign manager, John Podesta, among others.

But Mr. Snowden, a computer expert who previously worked for the National Security Agency and CIA, said the U.S. government isn’t being forthcoming with respect to supporting its claims, especially when compared to another recent security breach attributed to state actors.

“In the case of the hacking attack on Sony, the FBI presented evidence that North Korea was behind it. In this case they didn’t, although I am convinced that they do have evidence. The question is why?” Mr. Snowdenasked.

“I think the NSA almost certainly saw who the intruders were. Why wouldn’t they? But I am also convinced that they saw a lot of other attackers on there, too,” Mr. Snowden added.

As many as six or seven separate actors may have infiltrated the DNC, Mr. Snowden suggested, calling it a “big target” with apparently lax security.

“I think the reality here was the narrative shaping about the Russians,” added Mr. Snowden, who received political asylum from Moscow in 2013 and currently lives in the region as a lawful permanent resident.

Russian President Vladimir Putin apparently agrees with Mr. Snowden’s last point on account of previously labeling allegations of election hacking “hysteria” whipped up by Washington.

“Does anyone seriously think Russia can somehow influence the choice of the U.S. people? Is the U.S. some kind of banana republic?” Mr. Putin said last year. “The United States is a great power. Please correct me if I’m wrong.”

Mr. Snowden admittedly leaked a trove of classified intelligence in 2013 concerning the NSA and its international surveillance operations. He was subsequently charged with violations of the U.S. Espionage Act and theft by the Justice Department, but has evaded prosecutions by residing in Russia ever since.

Russia was the only country willing to grant Mr. Snowden asylum, he told Der Spiegel.

“I have been quite critical of the Russian government on Twitter and in my statements, and that probably doesn’t win me any friends. They haven’t bothered me in the period until now, but who knows what that will look like in the future,” he said.