In this file picture, US Gen David Petraeus appears before the US Senate Armed Services Committee, during his confirmation hearing to become the head of US and NATO forces in Afghanistan, in Washington. He heads to Afghanistan to take command of the war.
The affair was discovered by the FBI during an investigation into a possible breach of his email. The White House was informed of it on Wednesday.
Petraeus, an ex-US commander in Iraq and
Afghanistan, met President Barack Obama on Thursday and offered to resign.
“Such behaviour is unacceptable, both as a husband and as the leader of an organisation such as ours. This afternoon, the President graciously accepted my resignation,” Petraeus said in a statement on Friday.
The woman he was found to be involved with has been identified as Paula Broadwell, author of All In: The Education of General David Petraeus, a recent biography of the CIA director.