WASHINGTON--The U.S. Food and Drug Administration secretly monitored the private emails of staff doctors and scientists who alleged the agency was approving medical devices that posed a danger to patients, according to federal court documents.

In a lawsuit filed last week in U.S. District Court in Washington, six current and former FDA employees also claim the agency sought to repress warnings about potential corruption in device reviews by retaliating against whistleblowers who passed information to Congress and the news media.

FDA spokeswoman Erica Jefferson said the agency does not comment on ongoing or pending litigation.

FDA computers warn users, when they log on, that no one on the system has a reasonable expectation of privacy and that the government may intercept any data at any time for any lawful government purpose, the Washington Post reported on Monday. After FDA employees aired their concerns to the incoming Obama administration in January 2009, the agency began intercepting the emails they sent to congressional staff via government computers, using private Google and Yahoo email accounts, the documents allege.

The FDA also used spyware to capture electronic snapshots of staff computer screens, which the lawsuit says allowed the agency to obtain privately stored whistleblower reports and identify others involved in whistleblower activities.

The doctors and scientists maintain that their own actions were legal but that the FDA surveillance violated their constitutional rights to privacy and had a chilling effect on whistleblowing activities. The alleged surveillance lasted for two years.