(NBC News) - A two-year review by the House Intelligence Committee, backed by liberal Democrats and conservative Republicans, concludes that Edward Snowden was a disgruntled, serial liar who leaked for petty reasons, put American soldiers at risk and remains in continuing contact with Russian intelligence services.

The 38-page review, filled with redactions of classified material, does not accuse Snowden of being a spy, but it seeks to poke holes in nearly every aspect of his account of why he gave reporters reams of classified documents he obtained as a contractor — and trusted insider — with the National Security Agency.

Snowden immediately began denouncing the report on Twitter, saying its core claims were made "without evidence" and that it established nothing worse than he might have been hard to work with.

His lawyer, Ben Wizner, told NBC News he considers the report "a failed attempt to discredit Edward Snowden, whose actions led to the most significant intelligence reforms in a generation."

"The report wholly ignores Snowden's repeated and courageous criticism of Russian surveillance and censorship laws," Wizner said. "It combines demonstrable falsehoods with deceptive inferences to paint an entirely fictional portrait of an American whistleblower."

Rep. Adam Schiff of California, the ranking Democrat on the House Intelligence Committee, said, "Snowden and his defenders claim that he is a whistleblower, but he isn't, as the Committee's review shows. Most of the material he stole had nothing to do with Americans' privacy, and its compromise has been of great value to America's adversaries and those who mean to do America harm."

The report takes direct aim at Snowden's stated motives for what officials have called the most significant leak of national security information in American history.

Snowden has said that his "breaking point" was Director of National Intelligence James Clapper's false statement to Congress in March 2013 that the intelligence community was not collecting millions of records on Americans.

The report says that Snowden began downloading secrets eight months before, after a spat with his NSA supervisors.

The passage on Snowden's alleged contacts with Russian intelligence services is mostly blacked out, but it quotes the deputy chairman of a Russian defense committee in parliament, who said in June that Snowden did share information with Russian intelligence.

In terms of damage, the report says the Pentagon identified eight "high risk issues" stemming from the Snowden leaks, including information that would put troops at risk if, as U.S. officials assume, the Russian and Chinese militaries now possess it.

Snowden's disclosure that the NSA had been keeping phone calling records on nearly every American led to the overhaul of that program, and some other modest changes in the rules for U.S. surveillance.

But most of his leaks had little impact on how the NSA does business. His disclosure of the so-called PRISM program, for example — under which the federal government spies on foreigners by gathering data from U.S. internet providers — did not lead to the abandonment of that program, which is considered extremely valuable even though it incidentally collects some American data.

However, the law governing that program expires next year, and some commentators have wondered whether Democrats in Congress will support extending it under President Donald Trump.

Snowden has specifically denied cooperating with Russian intelligence. In 2014, he told NBC News during an exclusive U.S. broadcast interview that he had "no relationship with the Russian government at all" and was not a spy. He told Yahoo News he gave the Russians "the stiff arm."

He has been living in Russia since soon after he fled the U.S. in 2013.