Glastonbury Festival boss Michael Eavis is lamenting the booking of novelty group The Wombles for this year's event - and said it was a mistake.
But the furry litter-picking troupe - who had a string of hits in the mid 1970s - have stepped up a war of words by saying they will not be tidying up the site afterwards.
The reunited act - put together by composer Mike Batt - are lined up to play the Avalon Stage of the festival on June 26.
Eavis said he was "cross" about the booking which he claimed was "a bit of a mistake" that was out of his hands.
He told the BBC: "I've got about 25 stages and managers and bookers for each of the stages. I can't control every single one of them but I do get cross about that kind of thing."
The group's run of hits - in the wake of their BBC1 series - included four songs in the top 10, including Remember You're A Womble.
Batt said the band were eager to play but they had withdrawn their offer of litter collection.
"Of course, they are looking forward to it. They had been planning to tidy up the site afterwards but now aren't going to do that. But they are going to rock the place and I hope Michael will check them out and regret regretting it.
"He probably doesn't realise what a fantastic live band the Wombles are."
Headliners for this year's main Pyramid Stage at Glastonbury include Beyonce, U2 and Coldplay.