Blur and Gorillaz frontman Damon Albarn has dismissed Live 8, saying too few black artists are taking part and it may not be the best way to help Africa.
Performers should also be charged for taking part because they will receive so much free publicity, he told BBC Radio 4's Today programme.
But a Live 8 spokesman hit back, saying Albarn should "check his facts".
Live 8 said they wanted to get the most popular stars for the shows, which would feature a large "urban element".
However Albarn said it was the "greatest oversight" not to include many black and world music artists on the bill for the London gig.
"This country is incredibly diverse," he said. "More than ever, black culture is an integral part of society. So why is the bill so damn Anglo-Saxon?
Organisers are also planning a large event in Africa
"If you are holding a party on behalf of people, then surely you don't shut the door on them.
"It's insensitive and it also perpetuates this idea that Africa is separated in some way."
But the Live 8 spokesman said organisers did not simply want to "preach to the converted" by appealing only to world music fans.
"Bob Geldof's intention was to get headline-grabbing shows full of people who fill stadiums and arenas," he said.
"This is not [world music festival] Womad. We are not doing an arts festival."
Ms Dynamite, US rapper Snoop Dogg and Senegalese singer Youssou N'Dour are the only black artists currently due to perform in London on 2 July.
The US concert in Philadelphia will feature a string of African American stars including Stevie Wonder, 50 Cent and Jay-Z.
A large African event is also being planned, the spokesman added, although it is not confirmed.
Albarn also said there should be "some kind of tariff" on record companies.
"All the artists that play there will enjoy increased record sales - if they play a good gig, they will benefit from it," the singer said.
Artists should put pressure on their record labels to "genuinely show this is an altruistic act and that there is no self-gain in it".
"Because surely that negates... the message if there is," he said.
Albarn, who released an album with musicians from Mali in 2002, said he had not been asked to play at Live 8.
"I don't want to take part in an event that is so exclusive. Is this the most effective way to help Africa?" he said.
Live 8 treated Africa like it was "a failing, ill, sick, tired place", he said.
"My personal experience of Africa is that yes, I have witnessed all those things there.
"But it's incredibly sophisticated - the society and the structure of people's lives is as sophisticated, if not more sophisticated in some ways, than in the West."