Jack Vettriano's works are known around the world

The 230 paintings include 20 major works by Jack Vettriano and two pictures by Scottish colourist Samuel John Peploe never seen in public.

The collection will be displayed at Hopetoun House near South Queensferry, on Monday.

Sotheby's spokeswoman Mitzi Mina said global interest was expected in the sale.

The auction will include some of Vettriano's best-known works, such as The Red Room, with an estimated value of �100,000 to �150,000; Dressing To Kill, expected to fetch �100,000 to �150,000 and The Same Old Game, �120,000 to �180,000.

Ms Mina said: "Vettriano's astonishing success in recent years has been the subject of so much attention and this sale is likely to attract buyers from all corners of the globe.

"The works span the artist's entire career, cataloguing his enduring fascination with intimate moments in male-female relationships."

'Golden moment'

Head of Scottish paintings Andre Zlattinger said the sale of the Peploe paintings was also exciting as their true identity had only been discovered when a furniture expert was carrying out a routine valuation in a family home in Minnesota, USA.

He explained interest would be heightened because the works - Still Life With a Fan and Pink Roses in a Jug - were contained on both sides of a single canvas.

Another work by Peploe, Still Life With Pink Roses and Oranges, is expected to fetch �200,000.

The Singing Butler fetched �2.5m in a 2004 sale

"Samuel John Peploe was a key figure in the Colourist movement, and so the emergence on to the market of two important works - one a newly discovered work, the other one of the artist's finest still-life paintings - is a very significant event," he said.

"Peploe spent his entire career striving to create the perfect picture, obsessively working and reworking compositions, and lingering over the display at his local greengrocer's in search of the "perfect" orange or lemon to include in his composition.

"However elusive perfection may have seemed to the artist himself, critics concur that his works of the 1920s came closest to achieving this holy grail.

"It is somewhat surprising, then, that one of the artist's most accomplished works, executed at exactly that golden moment, should have languished for so long in obscurity."

Works by Cadell, Fergusson, Hunter, Redpath, Blackadder, Howson and Morrocco will also go under the hammer.

Last year, Vettriano's The Singing Butler painting fetched a record of �744,800 at auction. The estimate placed on the painting had been �200,000.

Meanwhile, more Vettriano paintings will go under the hammer in a sale by another auctioneer this week. Several of the artist's works will be part of a Bonhams' sale in Edinburgh on Thursday.