Hours after the ill-fated shuttle broke up, killing all seven astronauts on board, debris purporting to be from the wreckage started appearing on net auction sites such as eBay.
"People should not be collecting that at all," said Nasa spokesman Bruce Buckingham.
"We live in an evil world and there are people that will do those types of things," he added.
Strictly prohibited
Nasa has stressed that any shuttle debris is the property of the US Government and anyone caught removing it could face charges of theft and interference in a federal investigation.
Local police has been attempting to cordon off areas where debris has come to rest.
Wreckage has been found in more than 1,200 spots across eastern Texas and western Louisiana.
US auction site eBay has been removing such items as soon as they appear and has made it clear that such sales are strictly prohibited.
Legitimate memorabilia from past space missions have been soaring in value on eBay.
Collectibles marking the doomed space shuttle have also appeared on internet sites as people attempt to cash in on the disaster.
Some 1,525 items for sale came up on eBay on Monday morning when BBC News Online searched for items with the STS-107, the Nasa number for the doomed mission.
Most of the items seemed to be patches, mission programmes and photos of the crew.
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