Looking tired and a little shaken in an Instragram video, the Hollywood actor said he stood by his views on the proposed Santana Minerals open-cast gold mine and was glad he voiced them.
"What I wasn’t prepared for was the personal abuse I would come in for."
He said it started with Minister for Regional Development and Minister for Resources Shane Jones.
"He chose to make this personal and I’m baffled as to why he would do that."
Mr Jones was not the only person firing abuse at him, he said.
"The amount of personal abuse that came in online, all over the shop, was frankly very shocking and disturbing, including threats of physical violence."
When his video was posted on a Facebook page for mine supporters, the abuse continued.
One commenter said: "Ya better watch that cancer doesn’t come back Sam. Karma has a funny way of dealing with things".
Another called him a "self-centred w.....".
Sir Sam also referenced a recent article by Stuff columnist Damien Grant, who described him as "multi-millionaire actor, vintner and local activist, Sir Nigel (Sam) Neill", "a wailing" millionaire hobby-farmer with "a winsome grin", who is "worried about the happiness of the frogs".
The opinion piece said the mine would provide major economic benefit for the country and Sir Sam’s opposition to it seemed "odd".
Mr Grant questioned where the state would get the money from "when millionaire environmentalists use their fame to prevent the very economic activity that Aotearoa needs to pay for the cancer treatment".
"Life may find a way in the magical Garden of Eden inhabited by the super-wealthy of Hollywood, but in the real world, purchasing expensive pharmaceutical products, paying school fees and saving for a modest retirement requires well-paying jobs and tax revenue."
Sir Sam said the column was "extremely personal".
"He’s another one who doesn’t seem to think I deserve an opinion about anything.
"But I’ll have you note, that this man is a convicted fraudster - a neo-liberal convicted fraudster - so I think you should, in all fairness, take whatever he says with a grain of salt."
Mr Jones declined to comment.
Mr Grant said he was disappointed to hear Sir Sam had received threats over his opposition to the mine.
"A person’s ideas should be debated on their merits and free expression should not be chilled by this sort of abhorrent behaviour.
"[Sir Sam] found my column to be ‘extremely personal’.
"I regret this.
"While acknowledging that we cannot anticipate how our words will affect others, I disagree with his interpretation."
Mr Grant said he wished "Sir Sam well, but we disagree on the merits of this project".
