Online auction site eBay has said it plans to overhaul its feedback system and will ban sellers from leaving negative comments about buyers.
EBay said problems were occurring, and slowing down trade, when buyers left negative comments about sellers who then retaliated with their own views.
The move, which will affect users worldwide, has angered many sellers.
Sellers say it will leave them unprotected.
The feedback forum was introduced by Ebay founder Pierre Omidyar in February 1996.
In a message then, he said: "By creating an open market that encourages honest dealings, I hope to make it easier to conduct business with strangers over the net.
Critics of the changes argue that by taking away a seller's right to complain about a problem buyer they will have very little recourse for action when a sale goes wrong.
And they complain that by still allowing buyers to leave dissenting comments about sellers, eBay has skewed the whole trading process.
When both sides have equal access and rights to leave negative comments about each other it is a well balanced trading process, they say. However, eBay counters that problem buyers can still be dealt with.
"If a buyer doesn't pay, the seller can easily contact eBay, we will review any complaint and maybe remove the buyer," a spokesman said.
The changes aim to "improve the overall customer experience", eBay said.
It added that many buyers would not leave negative comments for fear that sellers would retaliate.
As a result, buyers and sellers may not get a fair picture of what is actually happening between trading parties.
It maintains that the majority of transactions go "swimmingly".
EBay says that only a minority of sellers leave negative feedback for buyers.