Japan widened a ban on beef to cattle from a second tsunami-hit region Thursday, citing elevated radiation levels in the meat of animals because of the ongoing Fukushima nuclear crisis.

Almost 3,000 cattle feared tainted with radioactive caesium have been shipped nationwide, slaughtered and sold after the animals were fed rice straw exposed to fallout from the more than four-month-old nuclear crisis.

After banning sales of cattle from Fukushima prefecture last week, the government extended the order to neighbouring Miyagi where, officials said, at least six contaminated animals have been identified.

The new order was announced by Chief Cabinet Secretary Yukio Edano.

"We will continue gathering information and conducting surveys as thoroughly as ever from a safety standpoint," the top government spokesman said about the possibility of the ban being expanded to other areas.

Affected animals have been sold since late March, weeks after the quake-tsunami sparked the nuclear accident, and much of the meat has been eaten in restaurants and school canteens and at family dinner tables nationwide.

The latest beef restriction follows bans on produce including some green vegetables, milk and dairy products, some river fish, mushrooms and green tea from some areas of Japan.

Japan has no centralised system to test for food safety from radiation and has relied on prefecturesand municipalities to carry out checks.

The Fukushima Daiichi nuclear plant suffered meltdowns and explosions after it was hit by a powerfulquake and massive tsunami on March 11, and it has since continued to release radiation into the air, soil and sea.

The beef scandal only surfaced this month when elevated caesium levels were found in Tokyo in meat from cattle shipped from a farm in Minamisoma, a town just outside the no-go zone around the nuclear plant.

The hay fed to cattle in Japan has been contaminated with up to 690,000 becquerels per kilogram, compared with the government limit of 300 becquerels.

Beef contamination has been shown to be as high as 2,300 becquerels per kilogram, compared to the government limit of 500 becquerels.

The government has been at pains to stress that standard servings of the contaminated beef pose no immediate health risk, but many consumers have turned away from Japanese beef and prices have dropped.

Shopping in a Tokyo supermarket on Thursday, housewife Hidemi Kawai, 27, expressed concern about the latest news. "I don't think the safety of domestic beef has been guaranteed yet," she said.

"We preferred domestic beef to foreign beef. Now, my family buys Australian beef."