Washington ? New tests have confirmed that a Texas animal that federal officials earlier declared to be free of mad cow disease actually had did have the brain-wasting ailment, the U.S. Agriculture Department announced Friday.

The definitive testing, done in England over the past two weeks, showed that the ailing animal, first flagged as suspicious in November, was infected with mad cow disease. The animal was retested after the inspector general of the USDA requested the additional check because of continuing concerns about the sample that had been dismissed by the agency.

USDA Secretary Mike Johanns said that officials were just now trying to learn more about the origins of the animal, but that there is no indication it was imported, like the only other animal that has tested positive for the disease in the United States. That would make the newly identified animal the first American-born animal found to have mad cow disease.

Johanns sought Friday to assure consumers that the American beef supply is safe, and that any suspect beef would have been kept off supermarket shelves.

But he acknowledged a number of embarrassing mistakes and oversights by the agency. In addition to misdiagnosing the diseased sample, officials apparently mislabeled the sample that later tested positive, officials said. According to USDA Chief Veterinarian John Clifford, a tag describing the breed of the infected animal was apparently mislabeled, an error that has slowed the process of determining where the diseased animal came from.

Agriculture Secretary Mike Johanns confirms another case of mad cow disease in the United States.

The Weybridge, England lab, considered the world’s best, made the diagnosis using two different tests – including one the USDA had also used when it declared the animal disease-free. USDA officials had previously said that the diseased animal escaped their notice because they performed only an immunohistochemistry test, or IHC, and not a Western blot test. Friday, Johanns said the Weybridge lab found the sample to be positive for mad cow using both types of test.

Johanns said that from now on, the agency will use both the IHC and Western blot tests on all samples found to be suspicious on an initial, rapid screening test for the disease. Some 388,000 animals have been subjected to that test, and only three have been found to be suspicious, Johanns said.

Scientists believe that mad cow disease is spread through the feeding of infected animal parts to other cattle. The United States banned that kind of feed in 1997, and Johanns said Friday he believed the infected animal was born before that time. In very rare cases, the disease has been passed to humans who eat the infected meat, and the result has always been fatal. There have been no known cases of the human variant of mad cow disease in the United States.

Friday’s announcement drew immediate and sharp criticism of the administration’s handling of mad cow disease, or bovine spongiform encephalopathy (BSE). The beef industry lost billions of dollars in exports when the first mad cow case was found, and critics said the administration has sought to minimize additional threats to protect the industry from a second crisis. Over the past week, some industry representatives had questioned the inspector general’s authority to order the additional tests that ultimately found the positive sample, and Johanns publicly agreed with some of their criticism.

“Now we know why USDA resisted having the suspect animal subjected to the most sophisticated BSE test,” said Carol Tucker Foreman of the Consumer Federation of America. “They were afraid the truth would come out. The public and the industry know that this animal was infected with BSE only because the USDA office of inspector general insisted that the additional test be done.

“The Administration’s response to mad cow disease appears to be more public relations than public health,” said Rep. Henry Waxman, D-Calif. “The Agriculture Department now says it’s taking aggressive steps, but just a few weeks ago the department was talking about easing the ban on downer cattle in the food supply and sharply reducing mad cow surveillance.

“Congress must investigate what went wrong, and the administration must finally enforce strong measures to protect against mad cow disease,” he said.

Industry groups had a different view. “The bottom line for consumers remains the same: Your beef is safe,” the National Cattlemen’s Beef Association said in a statement. “Scientists, medical professionals and government officials agree that BSE is not a public health risk in the United States. BSE infectivity has not been found in beef, including steaks, roasts and ground beef.”

“This test result should be seen for what it truly is – proof positive that the surveillance system for BSE in the United States is working,” said Patrick Boyle, president of the American Meat Institute. “The enhanced testing program that the government started on June 1, 2004 is part of the multi-firewall system that this county has undertaken for nearly 15 years to staunch BSE.”

The positive result will likely further complicate several already contentious issues. The administration, for instance, is eager to reopen the Canadian border to shipments of live cattle – a decision favored by some of the large beef packers with operations on both sides of the border but opposed by many American cattle farmers and feedlot operators who fear additional contamination from Canada. At least four mad cow disease cases have been identified in Canada.

In addition, the administration has sought to modify the ban on allowing “downer” cows into the food supply. It imposed the ban after the first mad cow case was uncovered in Washington state in late 2003. Downers, animals that cannot stand on their own, are at higher risk of having mad cow disease.

Ranchers and beef industry spokesmen have argued that some “downer” animals are not sick but get injured during transport, and so should be allowed into the food supply. But others have said that animals that fall during transportation are more likely to be sick, and so all should be excluded.

“The safety net put into place by the Agriculture Department in 2003 kept this sick animal out of the meat case,” said Wayne Pacelle, president of the Humane Society of the United States. “This case calls into question the reliability of USDA’s BSE testing program and demonstrates the need for a permanent ban on slaughtering animals too ill or injured to walk.”

Johanns said the department had not yet learned where the animal was born and spent its nine years of life. Earlier, however, the department identified the diseased animal as one previously reported in mid-November, and USDA records show that animal came from Texas.

USDA officials also acknowledged during Friday’s press conference that the agency lab in Ames, Iowa, had tested the sample three times with the IHC method. Two results were negative but one came up positive. Chief veterinarian Clifford said that because the method used in the third test was considered unvalidated and “experimental,” the positive finding was not included in the agency’s conclusions about the case.