HONG KONG— Google Inc. Executive Chairman Eric Schmidt reacted to reports that the U.S. government allegedly spied on the company's data centers, describing such an act as "outrageous" and potentially illegal if proven.

"It's really outrageous that the National Security Agency was looking between the Google data centers, if that's true. The steps that the organization was willing to do without good judgment to pursue its mission and potentially violate people's privacy, it's not OK," Mr. Schmidt told The Wall Street Journal in an interview. "The Snowden revelations have assisted us in understanding that it's perfectly possible that there are more revelations to come."

Mr. Schmidt said Google had registered complaints with the NSA, as well as President Barack Obama and members of the U.S. Congress.

"The NSA allegedly collected the phone records of 320 million people in order to identify roughly 300 people who might be a risk. It's just bad public policy…and perhaps illegal," he said.

When contacted Monday, the NSA referred to its statement last week that said recent press articles about the agency's collection had misstated facts and mischaracterized the NSA's activities.