The World Wide Fund for Nature urged the U.S. government on Thursday to immediately impose economic sanctions on Japan in response to its expanded whaling program.

Richard Mott, vice president of the nongovernmental conservation organization, told a Washington news conference that a Japanese fishing newspaper had reported the capture of a Bryde's whale by the Japanese whaling fleet in the northwestern Pacific.

U.S. Commerce Secretary Norman Mineta said Monday that Washington would impose sanctions against Japan if the country starts catching Bryde's whales or sperm whales under its expanded whaling program, which is purportedly for research.

"There is no longer any reason for the United States to delay action. President Clinton should impose sanctions immediately to avoid further killing," Mott said.

Six Japanese ships, defying strong protests from antiwhaling countries such as the U.S. and Britain, left Japan earlier this month to catch Bryde's whales, sperm whales and minke whales in the northwestern Pacific.

Japan reportedly decided to resume hunting Bryde's and sperm whales, both protected species, for the first time since 1987 because scientific data suggests their populations have recovered sufficiently to allow catches.

Under U.S. law, the commerce secretary can recommend that the president take punitive measures.