Paintings by Pablo Picasso, Piet Mondrian and Vincent Van Gogh went on display at Christie's in London on Thursday ahead of a May sale, with the auction house encouraging art fans to book viewings while museums remain closed in Britain.

The three oil paintings are the highlights of the upcoming "20th Century Evening Sale" on May 13 in New York. They were previously on show in Hong Kong.

The sale will be led by Picasso's 1932 work "Femme assise près d'une fenêtre (Marie-Thérèse)", a portrait of the artist's mistress, which is seen selling around $55 million.

"It's an incredibly iconic image. It hasn't been seen up at auction since 2013," Keith Gill, head of the Impressionist and Modern Art department at Christie's London, told Reuters.

"And the appreciation of Marie-Therese portraits, particularly from 1932, has very much grown since that time. So this will be a stand-out price for the artist."

Mondrian's "Composition: No. II, with Yellow, Red and Blue" makes its first public outing in nearly 30 years. The painting has been in private hands since it last appeared at auction in 1993, Gill said. It is estimated to sell in the region of $25 million.

"Mondrians of this quality, of this iconic sort of modernist image, are incredibly rare. The vast majority are in museums and ... we haven't had a Mondrian of this quality at auction since 2015," he said.

Van Gogh's "Le pont de Trinquetaille" is seen selling for $25 million to $35 million.

To see the artworks, visitors must book viewings online, with numbers capped in line with local COVID-19 restrictions. Under Prime Minister Boris Johnson's roadmap out of lockdown, museums are set to open doors from May 17.

"There is this perception that you have to arrive at the front door and be met by various security staff to walk in the building but Christie's is very much an open door policy," Gill said.

"This art may well disappear from view now for 20, 30 years. It is a fantastic opportunity for people to come and see art that is museum quality when unfortunately the museums are still not yet open."