For almost a century, an Irish government building in the heart of Dublin has hosted a secret sanctum: the banned books room.

The department of justice, on St Stephen's Green, did not grant public access, because the shelves contained 12,000 books deemed indecent or obscene.

It was a graveyard for titles condemned by the Censorship of Publications Board, a guardian of public morals which guillotined anything that smelled of sex or other corruptions.

Harold Robbins was interred. So too Ian Fleming, Edna O'Brien, Brendan Behan, Oscar Wilde, DH Lawrence, JD Salinger, John Updike, Iris Murdoch, F Scott Fitzgerald and many more.

Exhumation, however, is nigh. The entire collection is to be moved to the National Archives as part of the repeal of Ireland's censorship laws. The censors' notes, minutes and ledgers that detail why each book was banned will be made publicly available for the first time – a trove for researchers of social history and state control.

"The censors prohibited works that they saw as contravening or subverting public morality – anything that was seen as unwholesome or suggestive of sexual immorality," said Orlaith McBride, the director of the National Archives. "It was often just the innuendo of something that could have been perceived as likely to corrupt or deprave."

The volumes span 1926 to 1996 and encompass pulp fiction, high-brow literature and academic texts. References to family planning, contraception and violence were likely to elicit bans, said McBride.

So too did suggestive imagery, such as the cover of O'Brien's groundbreaking 1960 novel, The Country Girls. "It's very subtly done but you can see the contours of the female form. The issue wasn't just the contents but the image," McBride said.

Banned titles included classics such as Wilde's The Picture of Dorian Gray, Behan's Borstal Boy and Lawrence's Lady Chatterley's Lover, as well as pulpy paperbacks with titles such as The Baby Doll Murders, A Doctor and his Mistress and Torrid Tale of a Wicked Town.

Scholarly tomes such as Sexual Life in England Past and Present and arcane works such as The Collected Works of Pierre Louÿs, a Belgian poet of the early 20th century, also ended up in what was informally called the banned books room.

The censorship board adopted a broad definition of indecent and obscene, said Brian Hughes, a history lecturer at the University of Limerick's Mary Immaculate College.

"I think people would be very surprised seeing these books or reading some of these books to think that they were banned at all in the first place, because attitudes are quite different now. I think it suggests that certainly in terms of printed matter, the written word, there's a much more liberal society. It is a more secular society as well; that's part of it. But I think it's a wider process of attitudes towards sex, sexuality changing."

In 1926, soon after independence, the nascent Irish Free State established the Committee of Evil Literature, a five-man panel tasked with protecting public morals. It recommended a strict system of vetting that led to the Censorship of Publications Board – which, for a time, was led by a Catholic priest – and an appeals board.

The censors reviewed material that was submitted by members of the public and customs and revenue officers. They also sourced books through a subscription to the Times Book Club.

The periodicals and books that accumulated at what is now known as the department of justice, home affairs and migration will be moved after Christmas to the National Archives, where they will be conserved, catalogued and stored.

"Many are first editions, and because of sheer age in a vulnerable state, so they won't be available to the public," said McBride. People could source them online "and in all good bookshops", she said.

The censors' registers and notes, plus letters from the public and interest groups, were transferred this week, and are undergoing conservation in advance of becoming publicly available. McBride said: "They are the most interesting because they record the decisions and reveal the thinking behind the bans."