The festival programme will be announced this evening, but festival public relations team member Sam White confirmed yesterday Mr Hersh would be attending, along with New Zealand investigative journalist Nicky Hager.
Mr Hersh writes for New Yorker magazine on military and security matters, and according to biographical material won a Pulitzer Prize in 1970 for exposing the My Lai massacre - where American troops killed up to 504 unarmed South Vietnamese civilians in March 1968.
He also reported on the mistreatment of Iraqi detainees by American military police at Abu Ghraib prison in Baghdad in 2004.
Mr White said it was a ''coup'' to have Mr Hersh - ''a hard hitter'' - take part in its Aspiring Conversations event which runs alongside the artistic aspects of the festival.
''It just adds another dimension to an arts festival but the Aspiring Conversations is usually one of the highlights.''
Festival director Philip Tremewan described Mr Hersh as ''probably the foremost investigative journalist in the world''.
''He can talk about policies in areas that are of deep interest to us all.''
