Sen. Dianne Feinstein, chair of the Senate Intelligence Committee, on Thursday strongly challenged former National Security Agency contractor Edward Snowden's assertion that he voiced concerns to the agency about its intelligence activities before he began leaking government secrets.

"In April, we asked the NSA if they had any contacts with Snowden" regarding warnings he may have made about collecting metadata on Americans' phone calls and e-mails and about overseas spying, Feinstein said in a meeting with The Chronicle editorial board.

Although Snowden said he had "left a paper trail" of concerns about the NSA, that's not what the record showed, Feinstein said.

Snowden made the assertion during an interview with NBC News this week, his first ever on U.S. television. He said he had tried to raise concerns about NSA spying by going through channels at the agency before he leaked stolen documents.

But Feinstein showed Chronicle editors and reporters a copy of an April 2013 e-mail exchange between Snowden and the agency's general counsel, in which Snowden posed a question on NSA training regarding the relative authority of laws and executive orders.

Snowden referred specifically to an intelligence directive requiring that NSA activities be "conducted in a manner that safeguards the constitutional rights of U.S. persons." Agency training for following the directive, Snowden said, appeared to give equal weight to federal law and executive orders.

"I'm not entirely certain, but this does not seem correct, as it seems to imply executive orders have the same precedence as law," Snowden wrote. "Between (the orders) and laws, which have precedence?"

The general counsel's office reply began, "Hello Ed," and continued, "Executive orders have the 'force and effect of law.' That said, you are correct that (they) cannot override a statute."

The e-mail ended, "Please give me a call if you would like to discuss further."

The agency said it could find "no other relevant communication from Snowden." Two months after the April 2013 exchange, the first of Snowden's leaks was made public.

Feinstein said there appeared to be no additional evidence that Snowden "expressed concerns or complaints, in e-mail or any other form, about NSA's intelligence activities to anyone in a position of authority or oversight."

Snowden, however, told the Washington Post in a written response to questions that the e-mail release was "incomplete."

"The fact is that I did raise such concerns both verbally and in writing, and on multiple, continuing occasions - as I have always said, and as NSA has always denied," Snowden wrote.

Federal prosecutors filed espionage charges against Snowden last June. He left the country the month before and has been granted temporary asylum in Russia.

Feinstein said Snowden "should come back here and be part of the process."

"In many respects, I think that he's guilty of espionage," the senator said. "I do not regard him as a whistle-blower."

Snowden reportedly first worked as a security guard at an NSA-financed language research center at the University of Maryland. His computer skills got him jobs with NSA contractors, searching government computers for intrusions by hackers and foreign spies, according to media reports.

"There is a great deal of information" in the more than 1 million pages that Snowden leaked, Feinstein said. "It is fair to say American assets may well have been harmed," she said, as well as "America's relations with other countries."