The operator of Japan's tsunami-damaged nuclear power plant has been reprimanded and told to investigate how two workers were exposed to radiation levels more than twice a government-set limit.
The two men, one in his 30s and the other in his 40s, worked at Fukushima Dai-ichi's central control room for reactors three and four on March 11, when the tsunami struck, and the days that followed.
Tokyo Electric Power Co has said the workers are not showing immediate health problems but they will need long-term monitoring for an increased risk of cancer.
Soon after the tsunami damaged the plant, the government raised the lifetime radiation limit for men to 250 millisieverts from the earlier 100 millisieverts so workers could tackle the emergency.
The two men were confirmed last week as having exceeded that higher limit. A third worker is being tested further.
The Nuclear and Industrial Safety Agency reprimanded Tepco for violating the limit and ordered the company to take preventive measures within a week.
Workers have been fighting to get the plant under control since the earthquake and tsunami knocked out power and crucial cooling systems.