TOKYO - U.S. Ambassador Thomas Schieffer ate free samples of American beef Thursday at the first major Japanese supermarket to sell the meat after the lifting of a nearly three-year ban over worries about possible health hazards.

"Good," he said, after popping a slice of grilled steak into his mouth at a Seiyu, a supermarket chain owned by Wal-Mart Stores Inc.

"I've been waiting all week to come out here," he said, before purchasing steaks for his wife and himself.

Schieffer was visiting the Tokyo store with Seiyu Chief Executive Ed Kolodzieski, who also ate some of the beef for sale in the meat section, decorated with tiny American flags.

The return of American beef at Seiyu came ahead the resumption of sales Saturday at 20 Seiyu stores in the region near Tokyo.

Japan banned American beef imports in December 2003 after the first case of mad cow disease in the U.S. The ban was eased in December 2005, but tightened again the following month after prohibited spinal bones were found in a veal shipment.

Tokyo eased the restrictions again in last July year, but allows only meat from cows aged 20 months or younger. Japan also limits imports to beef that has been through stringent checks at selected U.S. meat processing plants.

Seiyu Ltd., 51 percent owned by Bentonville, Arkansas-based Wal-Mart, is the first major Japanese retail chain to start selling American beef. Seiyu operates about 400 stores here.

Other major chains have kept U.S. beef off their shelves, choosing instead to sell Japanese and Australian beef.

Aeon Co., Japan's biggest supermarket chain, has no plans to resume selling American beef, said company spokeswoman Kaori Watanabe.

"We are being cautious because we must consider how customers will be able to shop at our stores without worries," she said.

Kolodzieski, the Seiyu CEO, said the beef at the Seiyu stores is safe because special inspectors were sent to check on its quality.

"Our customers can come and find this terrific product from the United States," Kolodzieski said.

Imported U.S. beef is also far cheaper than Japanese beef. At Seiyu, American beef chuck for steaks cost $2.53 for 100 grams, or 3.5 ounces, according to the company. The same weight of domestic sirloin steak sells for about $9.15.

There was no identical beef product to compare prices directly.

Aside from Seiyu, a few other businesses have started selling U.S. beef here, including the five Costco stores run by the Japanese unit of U.S. warehouse retailer Costco Wholesale Corp. It is also being served in a popular beef bowl dish at fast-food chain Yoshinoya D&C Co.

Schieffer praised U.S. beef as safe and tasty. "There's a lot of Japanese customers who want to buy this product," he said.

He also urged Japan to raise the cutoff age of cattle to 30 months, instead of the current level of 20 months that the U.S. and Japan had agreed on. The 30-month level is a global standard observed by most other countries, Schieffer said.

A Japanese government spokesman defended the 20-month limit.

"We have this bilateral agreement," said Hiroshi Suzuki. "The Japanese government is responsible for making sure that the safety and security of the national diet will be maintained."

In Washington on Wednesday, President Bush urged Japan and South Korea - which also closed its market in 2003 - to reopen fully to U.S. beef imports.