Even low-level National Security Agency employees can look at citizens' communications, reporter and privacy advocate Glenn Greenwald said Sunday morning on ABC News' "This Week with George Stephanopoulos." 

“The NSA has trillions of telephone calls and emails in their databases that they’ve collected over the last several years,” Greenwald said. “And what these programs are, are very simple screens, like the ones that supermarket clerks or shipping and receiving clerks use, where all an analyst has to do is enter an email address or an IP address, and it does two things.  It searches that database and lets them listen to the calls or read the emails of everything that the NSA has stored, or look at the browsing histories or Google search terms that you’ve entered, and it also alerts them to any further activity that people connected to that email address or that IP address do in the future.”

Greenwald, who has taken the lead in reporting for the British paper The Guardian on revelations by NSA analyst-turned-leaker Edward Snowden, said the broad access allows for analysts to circumvent the legal system that is supposed to restrict the agency from engaging in certain surveillance activities without judicial oversight.

“There are legal constraints for how you can spy on Americans,” Greenwald told Stephanopoulos. “You can’t target them without going to the FISA court. But these systems allow analysts to listen to whatever emails they want, whatever telephone calls, browsing histories, Microsoft Word documents. ... And it’s all done with no need to go to a court, with no need to even get supervisor approval on the part of the analyst.”

The comments by Greenwald come as Snowden continues to navigate the process of figuring out what he will do for the rest of his life now that he is wanted by the American government. Snowden remains in a Moscow airport where he has been holed up for a month while he decides where to go. A number of countries have offered him asylum, but he has not accepted any such offers, instead keeping his options open as the Russian and American governments negotiate over his fate.

Dmitry Peskov, a spokesman for Russian President Vladimir Putin, said Friday that Russia will "not hand anyone over" to the United States, while U.S. Attorney General Eric Holder has promised that Snowden would not face the death penalty or torture if Russia were to extradite him to America.

Greenwald's comments on "This Week" came amidst the ongoing international tensions over Snowden, but U.S. Sen. Saxby Chambliss, R-Ga., said on the show that he was not aware of a program in which low-level analysts could access sensitive communications data of the sort Greenwald described.

“It wouldn’t just surprise me, it would shock me,” Chambliss said. “I was back out at NSA just last week, spent a couple hours out there with high-level and low-level NSA officials. And what I have been assured of is there is no capability. And at NSA, for anyone without a court order to listen to any telephone conversation or to monitor any email.”

Chambliss added that the U.S. government does not intentionally monitor emails, and that if any monitoring that takes place is "accidental," adding that he thought Greenwald's reporting was faulty.

“In fact, we don’t monitor emails. That’s what kind of assures me is that the reporting is not correct. Because no emails are monitored now,” Chambliss said. “They used to be, but that stopped two or three years ago. So I feel confident that there may have been some abuse, but if it was it was purely accidental.”