Francisco de Goya's Repentance is one of three drawings by the Spanish master that will be seen for the first time in more than 130 years when they go on show July 4 at Christie's in London. The Associated Press

Three Goya sketches will be seen for the first time in more than 130 years in July at Christie's in London where they are expected to sell for up to $6 million US.

The sketches, drawn between 1812 and 1829, were missing and presumed lost since an 1877 auction in Paris. It was only when their owners contacted the auction house about selling them that it was learned that they were in a private Swiss collection.

The three sketches, drawn between 1812 and 1829, are from Goya's personal notebooks, and are the most important group of the Spanish artist's sketches to come to auction in more than 30 years, Benjamin Peronnet, Christie's director and international head of old master and 19th century drawings, told the Reuters news agency.

He added that they are in "exceptional condition" because they had not been framed or exposed to light. The drawings are still on mounts used during the 1877 sale.

Witches and Women depicts four women fighting. Repentance portrays a seated man praying in front of a cross. The Constable Lampinos Stitched Inside a Dead Horse shows the punishment meted out to an 18th century local official by peasants for his persecution of women and students.

"They illustrate to perfection the inexhaustible fertility of Goya's imagination and the creativity and flair that sees him recognized as arguably the first modern artist," Peronnet said.

The drawings will be on show at Christie's for four days until they go on sale on behalf of the Swiss owners on July 8. They will be sold separately, but together they are expected to fetch up to $6 million US.

The owners said they did not realize the drawings were missing and are unclear how they got them.