Japan's government is set to suspend all cattle shipments from Fukushima as concerns over radiation-tainted beef escalate.
Senior Vice Health Minister Kohei Otsuka said beef from surrounding areas may also be affected.
It comes after 136 cows were found to have consumed feed affected by radioactive caesium.
This is the latest health scare linked to the Fukushima Daiichi nuclear power plant damaged by the March earthquake.
"The most likely outcome is that we will ban beef shipments," said Goshi Hosono, the cabinet minister responsible for the nuclear cleanup.
"We have to ensure food safety."
Increasing numbers of cows have been found to have consumed rice straw containing high levels of radioactive caesium.
The straw was harvested from rice paddies in Fukushima prefecture after the devastating earthquake and tsunami knocked out critical cooling systems at the local nuclear plant leading to a meltdown.
More than four months on, radioactive material continues to escape from the facility.
There have been no fatalities as a result of the crisis at Fukushima. However, more than 15,500 people died in the twin natural disaster and more than 5,000 are still missing.
Distributors across the country have bought meat from exposed cows and some of it could have already reached consumers.
The major supermarket chain Aeon said that hundreds of kilos of the beef has been sold at 14 of its stores in Tokyo and the surrounding areas.
The retailer said it would start to check beef shipments from all areas for contamination.
The government has also acknowledged that the problem could be wider than just Fukushima.
The initial discovery of contaminated beef was traced back to farms near the Fukushima power plant, but more recent discoveries are from farms as far as 100km (70 miles) away.
However, farm ministry officials said that consuming the beef a few times would not pose a health risk, despite radiation levels several times the national limit.
Shipments of certain vegetables from areas near the plant had already been halted due to high radiation levels.