MOSCOW, November 12 - RAPSI. CIA Director David Petraeus has submitted his resignation in response to his extramarital affair, which was revealed after his lover Paula Broadwell sent threatening emails to another woman. US President Barack Obama has approved his resignation.

Former US General David Petraeus, 59, was having an affair with Paula Broadwell, author of his biography "All In: The Education of General David Petraeus". His relations with the journalist became the subject of an FBI investigation after Jill Kelley, 37, a social planner for MacDill Air Force Base who lives in Tampa, Florida, complained to the bureau that she was receiving threatening emails.

Telegraph UK reported that Broadwell allegedly sent the emails out of jealousy. During the investigation, the FBI uncovered the correspondence between Broadwell and Petraeus and disclosed their love affair.

ABC reported that the Kelly and Petraeus families are long-time friends friends that met in Tampa, where he headed the United States Central Command headquarters from 2008 to 2010.

"We and our family have been friends with General Petraeus and his family for over five years. We respect his and his family's privacy and want the same for us and our three children," reads the statement by the Kelleys, posted on ABC's website.

A source close to both families told ABC that there was only friendship between Jill Kelley and David Petraeus.

Former General Petraeus became director of the CIA in early September 2011. He previously commanded NATO forces in Afghanistan and headed the U.S. military operation in Iraq.

He served 37 years in the armed forces.

He has been married to Holly Petraeus for 37 years. They met while David was studying at the United States Military Academy at West Point.