Kris Humphries Sicks FBI on Myla Sinanaj

Kris Humphries is no dummy when it comes to alleged extortion, because we've learned his lawyers contacted FBI agents Friday, claiming his ex-flame Myla Sinanaj tried to extort him by demanding a large sum of money, or else she'd release damaging information about their relationship to the media.

As we first reported, lawyers for Kris and Myla were jawboning Friday ... Kris' lawyers were trying to get her to sign a non-disclosure agreement.

As for why they want to muzzle her, sources connected with Myla say she has emails, texts and other documents chronicling their relationship that could hurt Kris if they became public.

Sources connected with Kris say ... Myla threatened that if she didn't get money she would "ruin" Kris. We're told the two sides could not reach an agreement, and that's when Kris' people decided to take it to the FBI.

Our Kris sources would not say whether the alleged extortion was in person, over the phone, via email or text, but we're told it is in some electronic form that would give the FBI jurisdiction to investigate the extortion allegation.