Criminal referrals for prosecutions relating to leaks have surged in the Trump administration — likely the result of a big increase in unauthorized disclosures of classified information, a leading intelligence watchdog says.

The number of leaks that were reported as potential crimes by federal agencies reached record high levels over the last two years, according to data released by the Justice Department last week and reported Monday by the Federation of American Scientists, which monitors the intelligence community.

There were 120 leak referrals for possible prosecution in 2017 and 88 in 2018, up from 37 in 2016 and 18 in 2015, the data shows. Only a small percentage of the cases are likely to be prosecuted.

Steven Aftergood, who directs the federation's Project on Government Secrecy, says the uptick is almost certainly due to the fact that under Trump, there is a lot more leaking going on. There has also been a renewed focus by the Justice Department in ferreting out leakers.

"I think it's because there are more leaks," Aftergood, who publishes a weekly newsletter on secrecy, said. "Agencies have been serious about leaks forever — it's not like they decided, 'Oh, we're going to suddenly start paying attention to this.' So the fact that it has escalated so sharply indicates that there is something qualitatively different."

Aftergood and other experts believe discipline about classified information has been diminishing. Trusted, cleared individuals at the CIA and the National Security Agency, including Edward Snowden, have disclosed a raft of secrets in recent years, and that phenomenon continues.

Harold Martin, an NSA contractor who had been taking home classified documents for years, was sentenced to nine years in prison last month although that was not a leak case. Reality Winner, an NSA employee in Georgia, was sentenced to more than five years in prison for leaking a classified document about Russian election interference to a news organization, the Intercept.

FBI agent Terry James Albury was sentenced to four years in prison in October after pleading guilty to disclosing to The Intercept news site classified documents related to the FBI's use of informants.

Yet there is no doubt, current and former intelligence officials say, that there has been an outpouring of leaks meant to push back against Trump administration policies, including the sorts of disclosures rarely seen before.

Two examples include the leaking of transcripts of Trump's phone calls with foreign leaders to the Washington Post, and the disclosures about irregularities in the way the White House processed senior presidential adviser Jared Kushner's security clearance to NBC News. It's not clear whether either case was referred to the Justice Department by a federal agency, although U.S. Rep. Devin Nunes, R-Calif., then chairman of the House Intelligence Committee, said he filed his own referral on the transcripts.

The transcripts highlighted what many believed was bizarre and unsettling behavior on Trump's part, and the security clearance disclosures showed that career officials had been overruled, something that rarely happens.

"In some cases, these are not leaks from deep in the military bureaucracy ... they're right out of the Oval Office, and that's pretty much unheard of," Aftergood said.

The Trump administration has averaged 104 leak referrals per year. By comparison, the average number of leak referrals during the Obama administration (2009-2016) was 39 per year, the federation found.

Then-Attorney General Jeff Sessions complained in August 2017 that there had been a "staggering number of leaks."

"Referrals for investigations of classified leaks to the Department of Justice from our intelligence agencies have exploded," Sessions said, as he outlined a new effort to stop them, including tripling the number of active leak investigations by the FBI.

Most leak referrals never result in prosecutions because leak cases are difficult to solve.

The Obama administration came under criticism for bringing an unprecedented number of criminal leaks cases, but officials said that was more a function of technology than a policy shift — email and other electronic communications left a trail of evidence that prosecutors could not ignore.

Of the 14 people who have been prosecuted under the Espionage Act for leaking secrets, eight were arrested under Obama's administration, according to Alexandra Ellerbeck, a researcher with the Committee to Protect Journalists.

Under Trump, in addition to Winner, a former CIA cyberoperative named Joshua Schulte was charged last year with disclosing CIA hacking tools to Wikileaks. And a senior Treasury Department official, Natalie Mayflower Sours Edwards, is accused of leaking sensitive documents to Buzzfeed. Both have pleaded not guilty.

The former head of security for the Senate intelligence committee, James Wolfe, was sentenced to two months in prison last year for lying to the FBI about media contacts in what began as a leaks case, although he was not accused of disclosing classified information.

In February, an Internal Revenue Service employee, John Fry, was charged with leaking confidential government reports describing financial transactions made by President Donald Trump's former personal lawyer Michael Cohen. He pleaded not guilty.

The cases point to the continuing tension between secrecy rules and a vigorous, free press. Government officials argue that leaks of classified information can put lives at risk, but many such leaks also serve a public interest in holding the government accountable for its secret actions.

The data on leaks referrals for prosecution, the Federation of American Scientists points out, "do not distinguish between leaks that simply 'hurt our country,' as the Attorney General put it, and those that are complicated by a significant public interest in the information that was disclosed."