A probe of the Food and Drug Administration’s e-mail surveillance of its employees widened Wednesday as the independent federal agency representing whistleblowers opened an investigation.

The FDA secretly monitored the private e-mail accounts of six scientists and doctors who had warned Congress and the White House that medical devices they were reviewing were approved or pushed toward approval despite safety concerns.

Among the communications, made on agency computers, were e-mails the employees wrote to the Office of Special Counsel, which reviews disclosures about government wrongdoing and retaliation against those who report it.

On Wednesday, attorneys for the employees and two prominent Republican lawmakers asked the special counsel to investigate whether the employees’ communications with the office, the Equal Employment Opportunity Commission and the inspector general that oversees FDA operations were protected under federal whistleblower laws. The attorneys and lawmakers say the e-mails were confidential and should not have been intercepted.

The special counsel’s involvement follows a federal lawsuit the scientists and doctors filed against the FDA in January, alleging that the government violated their constitutional privacy rights by intercepting their personal e-mail accounts to monitor activity they say was lawful.

“The confidentiality of these communications was broken,” said Stephen M. Kohn of the National Whistleblowers Center, whose firm is representing the plaintiffs. “As part of their official duties, they have the right to disclose confidential concerns. Employees throughout the government can work on these matters on paid time.”

The FDA tried but failed to have criminal charges brought against the whistleblowers for disclosing sensitive business information. The agency fired or harrassed the others.

Special Counsel Carolyn Lerner warned against government monitoring of email communications with her office.

“Monitoring employee e-mails with Office of Special Counsel or Congress could dissuade employees from making important disclosures,” Lerner said in a statement. “Monitoring communications with Office of Special Counsel is unacceptable.”

She encouraged other federal agencies to review their policies to ensure that they are not monitoring any disclosures--or impending disclosures-- of wrongdoing by whistleblowers.

Sen. Charles Grassley (R-Iowa) and House Oversight and Government Reform Committe Chairman Darryl Issa (R-Ca.) have opened their own probes into the e-mail monitoring, warning the FDA that interfering with a congressonal inquiry was illegal. On Wednesday they appealed to the special counsel to investigate apparent discrepancies in when the monitoring began.

Health and Human Services Secretary Kathleen Sebelious told Grassley at a budget hearing Wednesday that the FDA plans to cooperate with the special counsel’s investigation. She said that while “I certainly share your concerns about the potential for retaliation against whistleblowers,” the FDA “needs to have protections about proprietary information.”

The agency has warnings on its computers, visible when users log on, that employees have “no reasonable expectation of privacy” in any data passing through or stored on the system, and that the government may intercept any such data at any time for any lawful government purpose.

But Kohn said the warning itself is illegal since it does not ensure that employees who are preparing complaints to agencies that investigate wrongdoing have a right to have their private communications confidential.

The FDA said last week it began the surveillance in April 2010 to investigate allegations the employees leaked confidential information to the public. But documents obtained by the employees, who worked for the Office of Device Evaluation, showed contents of several e-mails from January 2009 between one scientist and a congressional aide.

The plaintiffs had challenged the safety and effectiveness of devices used in detecting colon cancer, breast cancer or other medical problems. Most of the devices were approved by supervisors after the scientists recommended against approval.

The inspector general’s office for the Department of Health and Human Services concluded twice that there was no evidence of criminal misconduct by the scientists.