FBI agents involved in the Hillary Clinton email probe were forced to sign a form that prohibited them from disclosing any information and made them subject to lie detector tests, according to bombshell new claims.

The bureau reportedly has confirmed to a senior Republican senator that agents were forced to stay quiet during the investigation after signing a "Case Briefing Acknowledgement" which states that any disclosure on the probe was "strictly prohibited."

"The purpose of this form is to maintain an official record of persons knowledgeable of a highly sensitive Federal Bureau of Investigation counterintelligence investigation," the agreement said, according to FOX News. The agreement also reportedly stated that those agents who signed the form could be subject to lie detector tests.

The New York Post reported that some agents never heard of the "Case Briefing Acknowledgement" form prior to working on the Clinton email investigation.  One retired FBI chief said signing the form prohibited him from speaking about the investigation publicly. "This is very, very unusual. I've never signed one, never circulated one to others," he claimed.

According to the post, many in the FBI were upset with director James Comey's decision not to prosecute Clinton for her mishandling of her private email server and said their boss has "managed to piss off right and left."  There is also allegedly suspicion in the bureau as the New York Post reported that "FBI agents believe there was an inside deal put in place after the Loretta Lynch/Bill Clinton tarmac meeting."

As RadarOnline.com reported, Bill Clinton secretly met  in a parked private plane in Phoenix only a few hours prior to the release of a controversial Benghazi report, a move that enraged both democrats and republicans.

But the secrecy agreement could also contribute to an attitude of "group think" and can have a "chilling effect" on agents, one retired FBI agent told Fox News.

Story developing.