"Mega did so proactively, as an exception, without a formal notice from the copyright owner or their agent," Mr Kumar said.
Internet mogul Kim Dotcom launched the Mega file-sharing site in January this year from his Coatesville mansion. He resigned as Mega company director in August to focus on other interests, including plans for a political party in New Zealand.
His wife, Mona, is a director of Mr KimDotcom Ltd and a director and shareholder in MD Corporate Trustee Ltd, the biggest shareholder in Mega.
Mr Elworthy said the discovery of Catton's work on the Mega site was the "tip of the iceberg".
"Just a few weeks ago we had to ask Mega to take down an entire educational textbook written by a New Zealand author ... which had been made available on their site. This type of illegal sharing is happening at an alarming rate and really hurting New Zealand creatives.
"While Eleanor Catton is doing big things for our international reputation, it's disappointing to see her being ripped off by a website which calls itself a New Zealand company," Mr Elworthy said.
Fergus Barrowman of Victoria University Press, which publishes The Luminaries, said the fact that a creative work was accessible on the internet free did not make it right to download it.
"We live in a digital age and authors and publishers recognise the changing nature of how readers want to access material.
"We made sure that The Luminaries was available as an e-book to New Zealand readers in a timely and accessible way, and we are delighted so many of them have taken advantage of this."