The agriculture ministry called for plant operator TEPCO to take measures.
The Fukushima Prefectural government revealed that last year's harvested rice from 14 locations in the city of Minami Soma contained more than 100 becquerels of cesium per kilogram. This is beyond the government's safety limit. The contaminated rice has been removed.
The ministry says cesium was detected on the outside of the husk. Debris removal work conducted last August at the Number 3 reactor may be one of the reasons for the contamination.
TEPCO reportedly told the ministry it will use chemicals to stop dust from spreading during debris removal work. The utility said it will increase monitoring of the spreading dust.
Neither the ministry nor the utility told Minami Soma City officials the work at the plant may have contaminated the crop.
City officials say they were greatly startled. They said the ministry should have explained the matter to local authorities much earlier.
The ministry says it was going to report the finding after it determined the cause.
TEPCO is scheduled to conduct a large-scale debris removal work at Number One reactor. For this, it plans to disassemble covers which had been put to prevent the radioactive materials from spreading.
Jul. 14, 2014 - Updated 05:47 UTC