A major exhibition of the work of Lucian Freud - described by art critic Robert Hughes as "the greatest living realist painter" - opened in London on Thursday.

Among more than 150 works on show at Tate Britain are 12 previously unseen paintings.

The new paintings include portraits of the artist's girlfriend, journalist Emily Bearn, who is more than 50 years his junior.

There is also a new self-portrait, completed just one month ago.

The exhibition has attracted much press coverage - most of it favourable - for the 79-year-old painter.

Freud's portrait of his grand-daughter Frances Costelloe

"Freud's last self-portrait is a grim, wonderful, extreme, unforgettable, unforgiving painting," wrote Adrian Searle in The Guardian.

"What a show," he added.

Curator William Feaver, who has been associated with the artist for three decades, said Freud attended the gallery "three or four times" during the preparations for the show - but found he did not need to change much.

"He adjusted one picture by about three inches and moved a couple of other pictures, but it was a happy collaboration," said Mr Feaver.

Some 30 of the works have not been seen in the UK before, as in recent years Freud's works are often bought by US collectors.

'Global fame'

"His dealer is over in New York," said Mr Feaver.

"Since the British Council put on an exhibition at the Hischhorn in Washington, it has really made his international reputation.

Self Portrait, Reflection: Only recently completed

"His great global fame has been since the early 90s," he added.

But one work is not hanging at Tate Britain - Freud's portrait of fellow artist Francis Bacon, which was stolen from a German gallery in 1988 while on loan.

It has yet to be traced, despite a poster campaign for its recovery.

Freud, born in Berlin, is the grandson of Sigmund Freud, the founder of psychoanalysis.

He came to England when he was a boy, his architect father having decided to escape the threat of Hitler's Germany.

Freud designed a poster to trace the lost Bacon work

He trained at the Central School of Art, London, the East Anglian School of Painting and Drawing, and Goldsmith's College, London, publishing his first work, a self-portrait, in an art magazine when he was 17.

Freud's powerful artistic vision first came to public notice in 1951, when his Interior At Paddington won a prize at the Festival of Britain.

For most of his career he has concentrated on gritty and realistic portraits, often nude, in which the subjects tend to be friends, relatives - or himself.

There is even a nude self-portrait at the Tate Britain exhibition, painted in 1993, in which he is wearing just boots to protect his feet from the paint.