The Nobel Prize medal of celebrated American geneticist and co-discoverer of DNA, James Watson, has sold for $5.68 million at an auction in New York.

The auction smashed the world record price for any Nobel Prize.

The medal sold for well above the expected price, estimated by auction house Christie's, of between $2.9 million to $4.18 million.

The famed medal, made of 23-karat gold featuring the profile of Swedish inventor Alfred Nobel, was the first to be put on sale by a living recipient.

Christie's did not disclose the buyer, who was bidding via telephone.

Francis Wahlgren, international director of books and manuscripts at Christie's said the price and record "demonstrate the growing strength in the market for the iconic pieces related to the early understanding and development of the implications of DNA and its growing relevance today".

Watson, along with Francis Crick and Maurice Wilkins, unravelled the double-helix structure and function of deoxyribonucleic acid (DNA) in Britain in 1953 in a discovery that heralded the modern era of biology.

The scientists received the Nobel Prize for medicine in 1962 for their groundbreaking work in genetics.

Watson, 86, said he planned to donate part of the proceeds to charities and to support scientific research.

A letter by Crick to his son sold for $US6 million in 2013, setting the world record for any letter sold at auction.

The missive, in which Crick outlined the structure of DNA shortly before the discovery was published, sold for more than three times the estimate.

Crick's Nobel medal fetched $US2.27 million when it was auctioned last year.

A 1936 Nobel Peace Prize medal sold for $US1.1 million last year.

AFP/Reuters