In a posting on his official congressional website, Sanders said he has written to the NSA director, Gen. Keith Alexander, to ask whether the agency has monitored telephone, email and Internet communication by others in Congress or in other elective offices.
"Has the NSA spied, or is the NSA currently spying, on members of Congress or other American elected officials?" Sanders asked in the letter.
The post on Sanders' website said spying includes "gathering metadata on calls made from official or personal phones, content from websites visited or emails sent, or collecting any other data from a third party not made available to the general public in the regular course of business?"
Sanders -- who has introduced legislation to restrict powers of the NSA and the FBI to secretly monitor Americans' electronic communications -- said he is "deeply concerned" by disclosures that the NSA has collected massive amounts of data on phone calls, emails and Internet activity "by millions of innocent Americans without any reason to even suspect involvement in illegal activities."
He said the United States "must be vigilant and aggressive" in protecting against terrorist attacks but noted a federal judge in Washington recently called the surveillance policies "almost Orwellian" in ruling the practice is likely unconstitutional.
The Obama administration Friday filed a formal appeal of the ruling.