Japanese authorities may have underestimated by 20 per cent the radiation doses workers got in the initial phase of the disaster at the Fukushima nuclear power plant, a newspaper reported, citing a United Nations panel.
A big earthquake and tsunami in March 2011 damaged the power station north of Tokyo, operated by Tokyo Electric Power Co (Tepco), causing three partial reactor meltdowns.
The company has struggled to contain leaking radiation at the site since then.
The UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) raised doubts about the dose estimates of the government and Tepco, in a summary of a report on Saturday, according to the Asahi.
UNSCEAR analysed radiation doses in 25,000 people who worked at the plant on or before October last year, using data provided by the government, Tepco and others, the newspaper said.
It determined that the tests used on workers did not take into account some types of radiation.
In particular, workers were tested for thyroid-gland doses from radioactive iodine after a significant delay, through procedures that failed to account for iodine-132 and iodine-133, which have short half-lives.
The Asahi said that if the UN panel's assessment was accurate, more workers would be eligible for free health checks. It did not give any detail of the implications on the health of the workers.