The Who's guitarist and songwriter Pete Townshend has accused film-maker Michael Moore of being a "bully" in a letter posted on his website.
Moore accused The Who star Townshend of being pro-war
Moore had wanted to use Townshend's song Won't Get Fooled Again on the soundtrack to his anti-Iraq war film Fahrenheit 9/11.
After Townshend refused, the guitarist, 59, claims Moore accused him of being in favour of the war.
Townshend said he resented the comments made by the documentary maker.
"I have nothing against Michael Moore personally... but I greatly resent being bullied and slurred by him in interviews just because he didn't get what he wanted from me," said Townshend.
"It seems to me that this aspect of his nature is not unlike that of the powerful and wilful man at the centre of his new documentary.
"He says that I refused to allow him to use my song Won't Get Fooled Again in his latest film, because I support the war, and that at the last minute I recanted, but he turned me down.
"I have never hidden the fact that at the beginning of the war in Iraq I was a supporter. But now, like millions of others, I am less sure we did the right thing."
Townshend added that his publishers originally refused the request to use the song as film producers Miramax offered "well below" the usual rate for music used in a film.
But despite offers to increase the rate, Townshend said he refused to let the Oscar-winning director use the song, because he was "not convinced" by the director's previous film Bowling For Columbine.
Townshend added: "I wish him all the best with the movie, which I know is popular, and which I still haven't seen.
"But he'll have to work very, very hard to convince me that a man with a camera is going to change the world more effectively than a man with a guitar."
Moore was reported on music website MTV.com as suggesting that some of Townshend's anger stemmed from when Moore turned down a request to make a film about The Who.