Spanish painter Francisco de Goya's stark portrayals of Spanish aristocrats, intellectuals and fellow artists in a major new exhibition at the National Gallery in London aims to show him as "the best ever portrait artist".

The exhibition, which opens on Wednesday, brings together from around the world around 70 portraits by the celebrated artist who lived between 1746 and 1828.

The works make up almost half of the 150 Goya portraits that still survive today, and account for a third of his total known output.

"Nobody has ever done an exhibition just with portraits because it's a bit risky. People might get bored," exhibition curator Xavier Bray told AFP.

But Bray said the show illustrates the variety of Goya's art from the energy and luminosity in "The Family of the Infante Don Luis de Borbon" to the gloominess of a self-portrait of the dying artist.

"Goya is eccentric as a painter. Sometimes the hands don't look right, sometimes the body looks a bit funny and English people are usually critical of these imperfections," Bray said.

"But the important thing is that when people leave they should think he is the best ever portrait artist... Manet, Picasso or Lucien Freud are in the same artistic tradition as Goya," he said.

Among the works in the exhibition is a series of self-portraits from different periods of his life which show his artistic evolution with age.

One of the highlights is the portrait of the duchess of Alba from 1797.

The portrait of the aristocrat dressed in black -- she was mourning the death of her husband -- has been one of the great mysteries of his work.

The words "siempre Goya" (Goya forever) can be seen by her feet.

In a biography on Goya, Robert Hughes saw this as a declaration of love for the duchess, who was rumoured to be his lover.

But Bray said it was most likely an expression of artistic authenticity.

"It means 'only Goya can paint me'. They had a platonic relationship. Goya was fascinated by this woman, who was extremely beautiful and also an eccentric. He was obsessed with her," he told AFP.

The Prado Museum in Madrid has loaned 10 paintings for the exhibition, which runs until January 10, 2016, with the others coming from Brazil, Mexico, Sweden and the United States.

Critics have responded mostly enthusiastically.

The Daily Telegraph called it "one of the shows of the decade".

It said the exhibition revealed "an artist whose unflinching portrayals of humanity still feel risky 200 years on".

"Goya had an enviable and slightly scary ability to make people look highly intelligent... and extremely stupid."
Source: AFP