Plants and animals making a comeback in Alaska's Prince William Sound in the two years since the Exxon Valdez oil spill might actually suffer from further cleanup efforts, according to an Exxon-commissioned study.

The report by three independent scientists recommended that the cleanup come to a halt."Further intrusive cleaning such as beach excavation and rock washing of beaches would kill plants and animals already there and set the recovery process back to the beginning," said the 31-page report that was released at a conference on oil spills in San Diego.