Since the last report in 2013, "no adverse health effects among Fukushima residents have been documented that could be directly attributed to radiation exposure from the accident", said Gillian Hirth, chairwoman of the UN's Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).

In a statement, the UN said the latest report had firmed up the 2013 research on the effects of radiation from the accident.

UNSCEAR said that a sharply higher rate of thyroid cancers detected among children exposed to the radiation was likely due to better diagnostics.

The UN's nuclear watchdog, the International Atomic Energy Agency, also said that there was no evidence that the disaster had had any detrimental effects on people's health.

"Though the ensuing damage caused nuclides to be released into the environment, scientists have found no evidence that this caused radiation-induced health effects," the head of the Vienna-based IAEA, Rafael Grossi, said in a statement.

However, "an important lesson of Fukushima is that regulators must be strong, independent and adequately resourced," Grossi said.

A magnitude 9.0 earthquake and a tsunami triggered the Fukushima disaster, which released large amounts of radiation into the air, earth and water around the nuclear power plant 220 kilometres (124 miles) northeast of Tokyo.

Around 100,000 people had to flee their homes and 19,000 were killed in the disaster.

Fukushima was the worst nuclear accident since the 1986 Chernobyl disaster in Ukraine, where larger numbers of thyroid cancers were also detected.