Bob Dylan's snub of his Nobel Prize in literature is "impolite and arrogant", according to a member of the Swedish academy that awards it.
The 75-year-old American is the first singer-songwriter to be awarded the prize.
Announcing the award on 14 October, the Swedish Royal Academy said he had "created new poetic expressions within the great American song tradition".
Dylan's 1960s folk and protest songs such as 'Blowin' in the Wind' and 'The Times They Are A-Changing' became anthems of the civil rights movement and Vietnam War protests.
Awarding the prize, the Swedish Royal Academy said: "Dylan has the status of an icon. His influence on contemporary music is profound."
Academy member Per Wastberg called him "probably the greatest living poet".
But all the academy's efforts to contact him since have failed, and he has not acknowledged the win in public.
"He is who he is", Per Wastberg said, adding that there was little surprise Dylan had ignored the news.
"We were aware that he can be difficult and that he does not like appearances when he stands alone on the stage," Mr Wastberg told Sweden's Dagens Nyheter newspaper in a separate interview.
A reference to the prize was removed from Dylan's website last week.
It is still not known if he will travel to Stockholm to receive the prize on 10 December, but if he does not, a ceremony marking his career will go ahead as planned, Mr Wastberg said.
Dylan is well known for his aversion to the media. In the 1960s he weathered the storm of protest that greeted his move to rock with 'Like a Rolling Stone', and his electric performance at the 1965 Newport Folk Festival, and he continues to record and perform for his millions of fans 50 years later.
Dylan always unconventional - English prof
Professor of English Literature at St Mary's University Twickenham, Allan Simmons, teaches classes on Bob Dylan.
He said Dylan's behaviour was not a surprise.
"Dylan has always behaved a bit like this, a little unpredictably, unconventionally.
"I wonder if one turned it around, the member of the Nobel committee who's challenging Dylan is perhaps setting himself up for a little bit of immortality, because Dylan - like all artists - mines his life, so perhaps Mr Wastberg will end up in in a Dylan song."
Mr Wastberg called the snub "unprecedented", but one person has previously rejected the Nobel Prize in Literature - French author and philosopher Jean-Paul Sartre, in 1964.
And one other recipient was distinctly underwhelmed by the honour.
On learning she had won the prize in 2007, having returned from doing her shopping in London, the Zimbabwe-born author Doris Lessing responded: "Oh Christ."
However, she did attend the ceremony later that year.