Directors Jules and Gedeon Naudet first premiered 9/11 on CBS in 2002 and have now updated the film with new interviews with rescue workers.
The Naudet brothers filmed the initial response of the Ladder 1 firehouse to the September 11 terror attacks, capturing one of only three known recordings of the north World Trade Centre tower being struck by a hijacked plane.
De Niro, who introduced 9/11 when it debuted on CBS nine years ago, will film a tour of the World Trade Centre memorial to be shown during the telecast.
Oscar-winning actor De Niro founded the Tribeca Film Festival in the wake of the 9/11 terror attacks to aid in New York City's recovery.
Jules and Gedeon Naudet's new cut of 9/11 will air at 8pm ET on September 11 on CBS.
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Watch a trailer for Jules and Gedeon Naudet's 9/11 below: