Nonetheless, its officials say, evidence of health and ecological risks justifies moving ahead.
The report also agreed with scientists who have criticized the agriculture department's handling of ecological risks.
Mr. Entis said the Food and Drug Administration had not specified what studies, if any, would be required that directly addressed such ecological risks.
But Mr. Adamov -- who criticized Ukraine last week for closing the Chernobyl nuclear power station, insisting it was perfectly safe -- denied that there were any ecological risks.
Since then, public concern about possible health and ecological risks of foods made with biotechnology has intensified in Europe and spread to other countries.
"The F.D.A. is not qualified to evaluate the ecological risks of engineered fish," said Dr. Jane Rissler, senior staff scientist at the Union of Concerned Scientists, a watchdog group that is a longtime critic of biotech regulation.
Plans to build the first offshore wind farm in the nation cleared a regulatory hurdle when a preliminary federal environmental review found that it would pose no major ecological risks.
Yet other administration officials said increasing concern over the handling of ecological risks by the three federal agencies that monitor biotech organisms had prompted consideration of a review of the current regulatory framework.
Human rights groups and environmentalists had earlier said the social and ecological risks had been grossly neglected, including impacts on biodiversity, aquatic ecosystems, greenhouse gas emissions, and implications for downstream communities.
Some of the biggest ecological risks come from cruise tourism, deforestation, overfishing and oil exploration.
There are some levels of both potential ecological risks and health hazards in the study area.
