Three exceptional drawings by Goya, the 18th-century Spanish artist, have been rediscovered after 130 years, to the excitement of art historians and collectors.

Such is their importance that they are expected to sell for more than £2 million at Christie's in London this summer.

All trace of the drawings, which had been in one of the artist's sketchbooks, had been lost since they were offered for sale in Paris in 1877. They were among 105 drawings dated back to 1796 and had been collected from sketchbooks whose pages he filled with studies of people in various moods and situations.

They do not relate to any known finished works.

In 1877 the 105 drawings sold for between 6 and 140 francs, far from outstanding prices, despite Goya's fame. Two of these three rediscovered examples even went unsold. Today the record for a Goya drawing stands at £1.3 million.

The three drawings emerged in Switzerland. The owners had not been aware that they had missing works by Goya until they decided to show them to Christie's. They cannot recall how or when they came into their family's possession.

The drawings are in exceptional condition because they have never been framed or exposed to light. Still on the mounts made for the 1877 auction, they bear pinholes from the tacks used to hang them unframed.

Benjamin Peronnet, international head of Christie's Old Master and 19th-Century Drawings, said: “We expect to attract the interest of international collectors and institutions who have rarely had an opportunity in recent years to acquire works by Goya of such importance.”

Goya (1746-1828) was the leading Spanish painter and etcher of the late 18th century, and court painter to the kings of Spain. His works include The Disasters of War, a series of etchings that record the horrors committed during the Napoleonic invasion.

The three drawings reflect his fascination for man's inhumanity to man. One of them, titled Down They Come, depicts four women fighting as they fly through the air. One has a broad smile and pulls the hair of another, who screams in pain.

Another drawing shows an anguished figure stitched into a dead horse. The image bears an extensive inscription in Goya's hand, in which he outlined the story behind it. In Saragossa, in the middle of the 18th century, the peasants revolted against a local official called Lampinos, who had been persecuting students and women in the city. Seeking revenge, the people stitched him inside a dead horse where, according to the inscription, “for the whole night he remained alive”.

The third, Repentance, shows a seated man praying, his eyes raised and his mouth open in an expression that prefigures Munch's Scream.

They will be offered at Christie's on July 8, after their display to the public from July 4 to 7.

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