US intelligence whistleblower Edward Snowden "has had and continues to have contact" with Russian intelligence services and his leaks were the largest public release of top-secret materials in US history, according to a newly declassified congressional report.
"Since Snowden's arrival in Moscow, he has had, and continues to have, contact with Russian intelligence services," according to the US House of Representatives Intelligence Committee report released on Thursday.
The US Defense Department found 13 undisclosed "high risk" security issues caused by Snowden's release to news organizations of tens of thousands of sensitive documents, the report said.
If Russia or China obtained access to information on eight of the 13 issues, "American troops will be at greater risk in any future conflict," said the report, which was largely blacked out.
The report was released after a recent CIA assessment that alleges hackers working for Moscow influenced the US presidential election in favor of incoming President Donald Trump.
Snowden has been living in Moscow since June 2013 after he released thousands of classified intelligence documents about US surveillance programs inside the country and around the world.
His leaks triggered an international furor over the reach of US spy operations.
Snowden, who worked for the CIA before being hired by a National Security Agency (NSA) contractor, criticized the report on Twitter, saying it was "rifled with obvious falsehoods."
In the tweet, he said the report presented no evidence that his disclosures were made "with harmful intent, foreign influence, or harm. Wow."
The new House report called Snowden's leaks "the largest and most damaging public release" of top-secret materials in US intelligence history.
It also criticized the US intelligence community for failing to thoroughly review all of the documents he released or to implement sufficient safeguards against future unauthorized leakers.
"The committee remains concerned that more than three years after the start of the unauthorized disclosures, NSA, and the IC (Intelligence Community) as a whole, have not done enough to minimize the risk of another massive unauthorized disclosure," the report said.
Shortly after the report was released, Snowden’s chief lawyer, Ben Wizner, said in a statement that the report was “petulant nonsense.”
“The House committee spent three years and millions of dollars in a failed attempt to discredit Edward Snowden, whose actions led to the most significant intelligence reforms in a generation,” Wizner said on Twitter.