Australian actor Tom Long, who starred in popular late-90s TV series SeaChange, has reportedly died after a long battle with cancer.

The Curb tweeted early Sunday that "the great Tom Long has left us".

The performer, aged 51, was diagnosed with multiple myeloma in 2012, and in March last year flew to the United States with his family to take part in a medical trial with just 17 other participants.

It is understood that he died of encephalitis.

Best-known for playing court official and keen surfer Angus in ABC TV's SeaChange, he was last seen in a professional capacity in 2012. In July that year, he collapsed on stage while performing in the historical play Coranderrk: We Will Show the Country at the Sydney Opera House.