The government issued a shipment ban Monday on all beef cattle from Iwate Prefecture after detecting radioactive cesium exceeding the state limit from a number of cows.

Iwate is the third prefecture to be handed down such orders, following Fukushima and Miyagi, raising nationwide concern over the spread of contaminated beef cattle. On Sunday it was reported that Tochigi could be next.

Farmers who fed their cattle contaminated straw must test all of their slaughtered beef, while other farmers must test at least one cow per ranch. The ban will be partially lifted if they pass the tests, Edano said, adding the government will make sure farmers are compensated.

"We would like to identify the beef cattle that is possibly contaminated as soon as possible . . . and take further measures to ensure that only those that have cleared the tests are distributed," Edano said.

Six cattle from two locations in Iwate Prefecture have so far tested positive for radioactive cesium above the safety limit of 500 becquerels per kilogram.

Last week, Iwate Prefecture announced it would screen all meat slaughtered in the prefecture from early August, and Gov. Takuya Tasso reportedly objected to the ban on Monday afternoon.

But Edano stressed that the shipment ban was necessary to protect food safety. If Iwate's test results prove to be "consistent with the conditions for partially lifting the ban, that means that the safety (of the beef) has been secured and we will lift the ban as soon as possible," he said.