Japan says it may allow certain nuclear reactors to remain in operation for up to 60 years after they were built.

The government in Tokyo had been considering tough new standards that would require all nuclear reactors to be shut down after they reach 40 years of operation.

But Chief Cabinet Secretary Osamu Fujimura said Wednesday that the government may allow nuclear operators to apply for a 20-year extension if they meet strict safety requirements.

Many of Japan's nuclear plants will soon approach the 40-year mark. Only a handful are currently in operation due to government-ordered stress tests following the disaster at the tsunami-struck Fukushima Daichi plant in March 2011.

Public anxiety about nuclear power is high in Japan, and many environmental rights groups see the move as an apparent backtrack from the government's promise of enhanced nuclear safety regulations. Greenpeace Japan called the government's plan “an unacceptable risk for the people of Japan, especially when they are already suffering ongoing effects from the triple meltdown at Fukushima.

Japanese officials say the 20-year extension for nuclear facilities is an internationally recognized standard.