After being married for over 37 years, I showed extremely poor judgment by engaging in an extra-marital affair.

CIA director David Petraeus has resigned from his post, admitting he had an extra-marital affair.

In a statement, Mr Petraeus said he had submitted his resignation to President Barack Obama, and that he had shown "extremely poor judgement".

He described his behaviour as "unacceptable" for the leader of the nation's main intelligence agency.