The New Zealander had in recent years undergone treatment for lymphoma but declared this year that he was cancer free.

"It is with immense sadness that the whanau of Sam Neill share the news of his passing on Monday 13 July, in Sydney Australia," the statement read, using the New Zealand Maori word for family.

"The loss was sudden and unexpected but blessed by the fact that Sam remained cancer free."

The statement did not elaborate on the cause of Neill's death, but said he had been treated at St Vincent's Private Hospital in Sydney.

"Sam was surrounded by family and passed with the dignity that has characterised his whole life," the statement said.

New Zealand Prime Minister Christopher Luxon said Neill was "one of the greats".

"For more than fifty years he took New Zealand stories to the world and his talents helped make our film industry into what it is today -- one of our greatest cultural exports," Luxon said in a statement.

"His work will be watched and loved long after all of us."

Australian Prime Minister Anthony Albanese said Neill held a "special place in Australian hearts".

"Wry and dry, thoughtful and laconic, Sam fought illness with the same dignity, humour and conviction that gave strength to his every performance," Albanese said.

"He will be much mourned and long remembered."

Fellow Kiwi actor Karl Urban said "Sam was truly brilliant", while Australian actor David Wenham said Neill was "the kindest, cheekiest, most generous and supportive friend going around".