Private letters released in Sweden to mark the centenary of the film star's birth throw a new and and tragic light on the tormented life of the pauper girl from Stockholm who became 'The Face' of Hollywood in the Thirties, made 27 films and spent the last 50 years of her life as a recluse.

But it was not merely the unrequited love for Pollak - with whom Garbo maintained a correspondence for 60 years - that overshadowed the star's life up to her death in 1990. Two exhibitions in Sweden and a new book reveal that, before she left for the 'uggly' [sic] United States in 1925, Garbo was self-obsessed, depressive and ashamed of her latrine-cleaner father.

Until now, Garbo, who was born in Stockholm on 18 September 1905, has been depicted as a happy-go-lucky girl who was turned into an ice maiden by what she called the MGM 'factory' - a film-making 'machine' into which she was launched in 1926 after her hairline and teeth had been straightened, her eyebrows plucked and she had been forced to lose 15kg (33lb). But research on her life before she left for the United States at 20 shows that, through her ambition and vanity, Garbo was at least as out of step with puritanical Sweden, where self-effacement is considered a quality above all others.

As part of preparations for an exhibition that opens on Friday at the Swedish Postal Museum in Stockholm, researcher Pernilla Astrom interviewed elderly people with memories of 'Katta' or 'Gurra' - Garbo's nicknames when she grew up in the poor Sodermalm quarter of the city. One, a former gymnast, recalled that Greta Gustafsson, as she was called, announced at the age of 10 that she wanted to be an actress 'because it's posh'.

Tin Andersen Axell, whose new book, Djävla Älskade Unge (Bloody Beloved Kid), is based on Garbo's letters to Pollak, says 'Gurra' was acutely aware of being the pleb of her drama school gang, and played on that. The title of Axell's book is based on the first words of a 1924 letter from Garbo to Pollak - whom she calls Mimosa - in which she writes: 'The letter from you has aroused a storm of longing within me.' The young actor - whose professional name, Garbo, is said to have been invented by Pollak - describes herself as 'slow, tired, boring' when far from her girlfriend.

Garbo remains as obsessed with Pollak - who by then is married - when writing from the US in 1928. 'I dream of seeing you and discovering whether you still care as much about your old bachelor. I love you, little Mimosa.'

Two years later, when Pollak announced she was pregnant, Garbo writes: 'We cannot help our nature, as God has created it. But I have always thought you and I belonged together.' Later, in a telegram to mark the birth of Pollak's son, Garbo writes: 'Incredibly proud to be a father.'

At least two men, Swedish publisher Lars Saxon and American silent film star John Gilbert, are said to have proposed to Garbo three times. But in a letter on MGM notepaper, obtained by the Postal Museum, she writes to Saxon: 'I will probably remain a bachelor all my life. "Wife" is such an uggly word.'

According to Ms Astrom, the Postal Museum had trouble gathering letters for the exhibition: 'The family - the Reisfields, descendants of Garbo's brother, Sven - are very ill at ease with the sexuality issue. Their feelings were not helped by claims from the writer Mercedes da Costa that she had a lesbian affair with Garbo. The claim could not be substantiated from the content of da Costa's letters from Garbo, published in 2000.'

The Garbo-Pollak exchange is more explicit and long-running, though it suffers from omitting Mimi's replies, believed to be in the Reisfield collection. But if further proof was needed of Garbo's preference for women, the Postal Museum has dug out a letter she wrote at 14 to a friend, Eva Blomgren. 'It seems to be written after a lovers' tiff, said Ms Anstrom.'