Actor James Gandolfini, best known for his portrayal of New Jersey mobster Tony Soprano in the hit HBO series "The Sopranos," died while on vacation in Italy, the actor's representatives told Efe. He was 51.

Initial reports indicated he died Wednesday of a massive heart attack.

Gandolfini had planned to attend Sicily's Taormina Film Festival, where he was to have taken part in a roundtable discussion on cinema this weekend with Italian film director Gabriele Muccino.

"It is with immense sorrow that we report our client, James Gandolfini, passed away today while on holiday in Rome, Italy," Mark Armstrong and Nancy Sanders, the actor's managers, said in a joint statement Wednesday.

"Our hearts are shattered and we will miss him deeply. He and his family were part of our family for many years and we are all grieving."

The actor, a native of Westwood, New Jersey who was of Italian descent, was the central character in HBO's hugely successful television crime drama "The Sopranos," which premiered in 1999 and ended its run of six seasons and 86 episodes in 2007.

The show, winner of 21 Emmys and five Golden Globe awards, was named early this month by the Writers Guild of America as the best-written television series of all time.

"Sopranos" revolved around Tony Soprano and his efforts to balance his dysfunctional home life with the demands of running a criminal organization.

"We're all in shock and feeling immeasurable sadness at the loss of a beloved member of our family. He was special man, a great talent, but more importantly a gentle and loving person who treated everyone no matter their title or position with equal respect," HBO said in a statement.

Gandolfini won three Emmys - in 2000, 2001 and 2003 - as a lead drama actor in a primetime series for his role as Tony Soprano, as well as a Golden Globe for best actor in a TV drama series in 1999 for his portrayal of that same character. EFE