NEW YORK (AFP) - A long-lost notebook owned by British mathematician and World War II code breaker Alan Turing sold at auction in New York on Monday for US$1 million (S$1.37 million), Bonhams auction house said.

The sale of the recently discovered notebook comes at a time of enormous interest in Turing's life and work generated by Oscar-winning movie The Imitation Game.

The manuscript, which sold for US$1.025 million in two minutes of bidding, dates back to the mid-1940s when Turing was working to break the Nazi Enigma code at Britain's Bletchley Park.

An original 1944 Enigma Machine, still fully operational, sold for US$269,000 at the same auction, smashing pre-sale estimates of US$140,000-180,000.

Both winning bids were in the room, but both buyers wanted to remain anonymous, the auction house said.

Turing was a computer scientist, philosopher and cryptologist ahead of his time who played a crucial role in breaking Enigma.

"We have no idea how many lives he saved. It is estimated that he shortened the war by two years," said Cassandra Hatton, director of Bonhams' history of science and technology department.

The notebook is believed to be the only extensive Turing autograph manuscript in existence and gives an insight into the man whose work, when he was just 24, led to the universal computer machine.

It features 56 pages of Turing's notes on the foundations of mathematical notations and computer science, made during his leisure time at Bletchley Park.

It shows that Turing was examining the works of German philosopher Gottfried Wilhelm Leibniz, and French philosopher and mathematician Rene Descartes, among others.

Turing was prosecuted for homosexuality in 1952 when it was a crime in Britain. Forced to undergo chemical castration, Turing killed himself in 1954 at the age of 41.

He was officially pardoned by Queen Elizabeth II only in 2013, six decades after his death.

British actor Benedict Cumberbatch, nominated for an Oscar for portraying Turing in last year's film, has described the prospect of being able to hold one of his manuscripts as "thrilling".

The notebook was bought from a stationers in the English university city of Cambridge, where Turing was a fellow at King's College.

It was among papers left by Turing after his death in 1954 to friend and fellow mathematician, Robin Gandy.

On blank pages of the notebook, Gandy wrote a journal in which he called Turing a "dead father figure." Bonhams said the document remained hidden among Gandy's personal effects until his death.

Before the sale, Hatton told AFP that she hoped the notebook can be made available to researchers.

"What I really, really hope for is that a collector buys it and makes it available to an institution, at least loans it for a few years and makes it available to scholars," she said.

Andrew Hodges, who wrote the biography that inspired The Imitation Game said Turing was "parsimonious with his words and everything from his pen has special value.

"This notebook shines extra light on how, even when he was enmeshed in great world events, he remained committed to free-thinking work in pure mathematics."

Bonhams said a portion of the proceeds will be donated to charity.

The Imitation Game won an Oscar in February for best adapted screenplay. It had been nominated for eight Academy Awards.