John Allen (r) and David Petraeus (l)
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Petraeus scandal engulfs US Gen John Allen

13 November 2012 Last updated at 19:44 GMT

The top US commander in Afghanistan, General John Allen, is being investigated in connection with the scandal surrounding the former CIA director David Petraeus.

He is alleged to have sent thousands of "inappropriate emails" and other documents to a woman in contact with General Petraeus's mistress.

Steve Kingstone reports from Washington.