Prime Minister Naoto Kan on Thursday told Fukushima Gov. Yuhei Sato to slaughter all farm animals within a 20-km radius of the stricken Fukushima No. 1 nuclear plant.

The government's decision last month to formally declare the 20-km evacuation zone around the plant off-limits has been preventing farmers from feeding their livestock, leaving them to starve.

According to the farm ministry, there were an estimated 3,500 cows, 30,000 pigs, 675,000 chickens and 100 horses in the hot zone before the March 11 disasters threw the power plant into chaos.

Chief Cabinet Secretary Yukio Edano said the irradiated farm animals will be killed only if the owners give consent.

The animals "will weaken and starve to death, and leaving them in such a situation is also hard on the owners who bred them," Edano said. The government's decision "may meet with a lot of criticism but we decided to take responsibility and signal a policy instead of forcing this difficult decision onto the owners," he said.

Edano said the owners will be compensated financially by Tokyo Electric Power Co., manager of the crippled nuclear complex.

"Naturally, animals that were put to sleep because of the government's instruction will require that compensation be made," Edano said. "We are very sorry that the owners will suffer even with the financial compensation, but we are hopeful that Tepco will compensate them promptly."

If an owner refuses to provide consent, however, the government cannot put the animals to sleep.

"We would be entering the owners' land and the animals are their property — we cannot get rid of them without permission," a ministry official said. "I think we will just have to keep explaining why we are doing this . . . and seek their understanding."