In August, Japanese researchers, using data from the first survey conducted into the potential health impacts caused by the Fukushima nuclear disaster, concluded that 57 children had thyroid cancer as a direct result of radiation leaked by the reactors.
However, a further four children, then aged from between six and 17, but not counted by the first survey, have been included in a second survey as also suffering from the disease, according to Xinhua.
In March 2011, a 14-meter (46-foot) tsunami caused by a 9.0-magnitude earthquake hit the Fukushima Daiichi nuclear plant, causing several of the plant's reactors to melt down. The disaster also resulted in a major leakage of radioactive materials.
The accident displaced around 160,000 people and is reported to be the largest nuclear accident since the Chernobyl disaster in 1986.