Asked by reporters if it would ban all animal protein from cattle feed, Crawford said, "Something like that."

The FDA is in the final stages of preparing the new rule, which will supersede what was proposed by the agency more than a year ago, he said.

"It will be quite a bit stronger and will be out very soon," Crawford said. He refused to elaborate.

FDA spokesman Mike Herndon said the agency remains on track to release the proposed rule during the next month or two.

"I've never heard anything ... that would change the opinion on that," he said. Herndon declined to discuss details of the upcoming rule.

The FDA, which oversees animal feed, said last month it was considering a broader ban on use of poultry litter, table scraps and cattle blood in feed, as well as more restrictions on use of items thought to carry the highest risk of spreading mad cow.

Always fatal, bovine spongiform encephalopathy is believed to be spread among cattle through consumption of feed that contains material from infected cattle. People can contract a human version of the disease by eating contaminated meat.

Tom Cook, president of the National Renderers Association, said the trade group remains skeptical that any FDA rule would go so far as to ban all animal protein from cattle feed.

"We're not anticipating that. I think Dr. Crawford is just being ambiguous" with his comments today, said Cook.

"I don't think anybody knows exactly what the FDA's proposing. Dr. Crawford is going to be very careful about what he says in specifics before something comes out," he added.

The major US safeguard against mad cow disease is a 1997 ban on using the remains of cattle as a protein supplement in cattle feed.

Other safeguards include a prohibition against slaughtering "downer" cattle -- animals too sick to walk on their own -- for human food, and a requirement for meatpackers to remove from carcasses the brains, spinal cords, nervous tissue and other parts most likely to contain the malformed proteins blamed for the disease.

Last month, the US government wrapped up its investigation into the first domestic US case of mad cow disease, diagnosed in a Texas animal in June. It concluded that the animal was infected before the 1997 livestock feed ban was adopted.

It was the first US-born cow found with BSE and the second US case overall. The earlier case was found in December 2003 in a dairy cow imported from Canada to Washington state.