Bob Geldof has reacted with fury to news that Live 8 tickets are up for sale on eBay.
The star branded it a "disgrace" and accused the sellers of "disgusting greed."
He called for a worldwide boycott of eBay - describing the online auction site as an "electronic pimp".
And he is considering launching a court action to stop what he describes as "sick profiteering".
More than 100 pairs of tickets are up for sale so far and have already attracted bids of up to £1,000.
Geldof said: "I am sick with this. It is a disgrace. It is completely against the interests of the poor. The people who are selling these tickets on websites are miserable wretches who are capitalising on people's misery."
But a spokeswoman for eBay said: "The reselling of charity concert tickets is not illegal under UK law, so Live 8 tickets are allowed to be resold on eBay."
"As we do not wish to profit from this event, we have offered to make a donation to the Live 8 organisers at least equivalent to the fees we collect from the sale of Live 8 tickets," she added.