Despite the widened field, British writer Howard Jacobson, the 2010 winner, is the bookmakers' joint favourite with "J", alongside compatriot Ali Smith, who makes the shortlist for the third time with "How to be Both".
The US authors nominated are Joshua Ferris with "To Rise Again at a Decent Hour" and Karen Joy Fowler for "We Are All Completely Beside Ourselves".
They are joined by Australia's Richard Flanagan with "The Narrow Road to the Deep North" and Britain's Neel Mukherjee for "The Lives of Others".
"These six exceptional books take the reader on journeys around the world, between the UK, New York, Thailand, Italy, Calcutta and times past, present and future," said philosopher A. C. Grayling, the chairman of the judges.
"We had a lengthy and intensive debate to whittle the list down to these six. It is a strong, thought-provoking shortlist which we believe demonstrates the wonderful depth and range of contemporary fiction in English."
- 'World's foremost literary award' -
The annual Booker Prize was until now awarded for the best original full-length novel written in English by a citizen of the Commonwealth, the Republic of Ireland or Zimbabwe.
But this year the judges widened the field to any author writing originally in English, so long as their novel is published in Britain within the 12-month entry period.
The move was a bid to stamp the prize's authority as the English-speaking world's foremost literary award.
Judges said the strong British presence on the shortlist was not the result of tokenism, and insisted that fears that the prize would be "flooded by quality American novels to the detriment of everything else" had been unfounded.
The winner receives £50,000 ($80,000, 62,000 euros) and the award all but guarantees an upsurge in book sales and worldwide readership.
New Zealand author Eleanor Catton won the 2013 prize with her novel "The Luminaries".
Literature professor Sarah Churchwell, one of the six judges, said that while historical novels had dominated previous shortlists, "fiction about the contemporary moment and the recent past is making a resurgence".
"These are all very contemporary novels. The contemporary is coming into its own and finding its teeth again," she said.
This is the 46th year of the prize, which began in 1969.
The winner will be revealed at a ceremony in London's Guildhall on October 14.
2014 Booker Prize shortlist:
Joshua Ferris (USA) -- "To Rise Again at a Decent Hour"
Richard Flanagan (AUS) -- "The Narrow Road to the Deep North"
Karen Joy Fowler (USA) -- "We Are All Completely Beside Ourselves"
Howard Jacobson (GBR) -- "J"
Neel Mukherjee (GBR) -- "The Lives of Others"
Ali Smith (GBR) -- "How to be Both"
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The US authors nominated are Joshua Ferris with "To Rise Again at a Decent Hour" and Karen Joy Fowler for "We Are All Completely Beside Ourselves".
They are joined by Australia's Richard Flanagan with "The Narrow Road to the Deep North" and Britain's Neel Mukherjee for "The Lives of Others".
"These six exceptional books take the reader on journeys around the world, between the UK, New York, Thailand, Italy, Calcutta and times past, present and future," said philosopher A. C. Grayling, the chairman of the judges.
"We had a lengthy and intensive debate to whittle the list down to these six. It is a strong, thought-provoking shortlist which we believe demonstrates the wonderful depth and range of contemporary fiction in English."
- 'World's foremost literary award' -
The annual Booker Prize was until now awarded for the best original full-length novel written in English by a citizen of the Commonwealth, the Republic of Ireland or Zimbabwe.
But this year the judges widened the field to any author writing originally in English, so long as their novel is published in Britain within the 12-month entry period.
The move was a bid to stamp the prize's authority as the English-speaking world's foremost literary award.
Judges said the strong British presence on the shortlist was not the result of tokenism, and insisted that fears that the prize would be "flooded by quality American novels to the detriment of everything else" had been unfounded.
The winner receives £50,000 ($80,000, 62,000 euros) and the award all but guarantees an upsurge in book sales and worldwide readership.
New Zealand author Eleanor Catton won the 2013 prize with her novel "The Luminaries".
Literature professor Sarah Churchwell, one of the six judges, said that while historical novels had dominated previous shortlists, "fiction about the contemporary moment and the recent past is making a resurgence".
"These are all very contemporary novels. The contemporary is coming into its own and finding its teeth again," she said.
This is the 46th year of the prize, which began in 1969.
The winner will be revealed at a ceremony in London's Guildhall on October 14.
2014 Booker Prize shortlist:
Joshua Ferris (USA) -- "To Rise Again at a Decent Hour"
Richard Flanagan (AUS) -- "The Narrow Road to the Deep North"
Karen Joy Fowler (USA) -- "We Are All Completely Beside Ourselves"
Howard Jacobson (GBR) -- "J"
Neel Mukherjee (GBR) -- "The Lives of Others"
Ali Smith (GBR) -- "How to be Both"
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