Wales' foremost artist, Sir Kyffin Williams, has launched an attack on the art on show at the National Eisteddfod.
Sir Kyffin Williams has been unable to practise his art for 18 months
Royal Academician Sir Kyffin, who says his cancer treatment is going well, claims work on display at Faenol near Bangor, bears no relation to fine art.
He said "solid Welsh people" at the cultural festival would be turned away by what they saw.
But both the eisteddfod and its partner the Arts Council of Wales defended the festival's artworks.
Sir Kyffin, who is 87, has been fighting both lung and prostate cancer and has only recently been able to resume drawing again at his home in Anglesey.
He said he had not been able to attend this year's eisteddfod yet but hoped to attend on Friday.
But he said he had had seen reports on television of what was on show this year and said it was "absolutely awful."
"You have not got any fine art, which is something which has been practised down the centuries by artists and sculptors.
"All the new art work is something that anyone can do like fly-fishing or golf.
"It means absolutely nothing and anybody can do it," said Sir Kyffin, who has made outspoken attacks on modern art in the past.
"It's not the eisteddfod's fault - it's the fault of the Welsh arts council who sponsor the art there.
"They want to destroy art... it's all absolute nonsense really."
Sir Kyffin said he had been trying to get the arts council "to see sense for years" and had been down for a meeting in Cardiff.
The eisteddfod has defended the standard of art on show
"The solid Welsh people will go there (to the eisteddfod), have a look and go away again."
Exhibitions of older work are planned for next summer at galleries in London and Cardiff.
Geraint Talfan Davies, chairman of the Arts Council of Wales, which is sponsoring this year's art in the eisteddfod pavilion, said: "We have great respect for Sir Kyffin Williams as an artist and he is entitled to his own opinion of the exhibition.
"However, we also acknowledge he has much difficulty with contemporary art."
Eisteddfod visual arts officer Robyn Tomos said he would "agree to disagree" with Sir Kyffin.
"I'm very pleased with the exhibition in the pavilion this year," said Mr Thomas. "We have got a number of young people represented - up-and-coming young artists."
He said he was also pleased that two festival gold medals - in fine art and craft and design - had both been awarded at this year's eisteddfod along with the full monetary prize of £5,000.
Both winners were also representing Wales on the international stage, he said.
Sir Kyffin is renowned internationally for his oils and drawings, many of them scenes of his native Snowdonia. Two of his works from a visit to Patagonia in the 1960s are being auctioned at the eisteddfod on Friday to raise money for a school there.
"It's a good cause," said Sir Kyffin. "I got very fond of the people there. I was there for four months and did 700 drawings and about 40 oils.
This year, for only the second time in 40 years, he has been unable to exhibit at the Royal Academy in London due to his health, but two exhibitions of his work in Cardiff and London are planned for next summer.
"I'm doing drawings out of my head," he said.