The manuscripts were found on the street in the 1960s

Capote is said to have worked on Summer Crossing in the 1940s, but put it aside in 1950. It was never published.

The first draft was found at the bottom of manuscripts and photos by Capote's former house sitter.

"It's a kind of pre-Breakfast at Tiffany's," said Sotheby's expert Justin Caldwell.

Summer Crossing is the story of a 17-year-old girl who is left in New York while her parents take a holiday in Europe.

The manuscript, contained in four notebooks and 90 loose sheets, was left behind when Capote, who died in 1984, abandoned his Brooklyn apartment after the success of 1966's In Cold Blood.

The house sitter retrieved the box of manuscripts from the pavement outside the flat.

'Remarkable discovery'

Sotheby's expects it to sell for between $70,000 (�36,700) and (�52,450).

Breakfast At Tiffany's is Capote's most famous work

The auction also includes other work found in the box, including a draft of Capote's first published novel, Other Voices, Other Rooms, and two short stories, The Diamond Guitars and The Bargain.

Mr Caldwell said the discovery of Summer Crossing was "a remarkable literary discovery".

"It will undoubtedly provide valuable insights into this major writer's formative years as work on the novel occupied Capote both before and after Other Voices, Other Rooms," he said.

A decision on whether or not Summer Crossing will be published will be made by Capote's literary executor, Alan Schwartz.

But Capote biographer Gerald Clarke said that if the author himself did not think the work was fit to be published, then his wishes should be respected.

"This may not be something that should be published, because Truman himself did not feel it was worth publishing," he said.

"But it would still be of interest to writers and scholars."