No federal cyber stalking charges will be brought against Paula Broadwell, the biographer and mistress of former Central Intelligence Agency (CIA) director David Petraeus, whose extramarital affair with Petraeus led to the latter's abrupt resignation last month, according to local media.

Broadwell, whose alleged threatening e-mails to Jill Kelley, a socialite based in Tampa, the US state of Florida, led to an investigation by the US Federal Bureau of Investigation (FBI), has been under probe that may lead to criminal charges.

In a letter to Broadwell's attorney Robert Muse, Assistant US Attorney W. Stephen Muldrow wrote that his office had decided not to press federal charges against Broadwell relating to "alleged acts of cyber stalking," said a report carried by USA Today Tuesday.

In a brief statement, Muse said he and his client were "pleased with the decision."

Petraeus is a retired four-star general who served more than 37 years in the US Army. He had overseen all coalition forces in Iraq and led the military campaign in Afghanistan. Petraeus started to serve as CIA director in September 2011 until November 2012 when he resigned from the post after his extramarital ties with Broadwell came to light.

FBI began investigating the case after Jill Kelley, a friend of the Petraeus family, complained to law enforcement officers about receiving anonymous and threatening emails. The FBI traced the emails to Broadwell and found out the intimate relationship between Broadwell and Petraeus.

Petraeus has admitted in an interview with CNN that he had made "big mistakes" in the newly disclosed scandal, but insisted that he had never passed any classified information to Paula Broadwell, his biographer.

US lawmakers on both sides have criticized the FBI for not notifying the Congressional intelligence and security panels of the probe into Petraeus's scandal.