Japan's Fukushima prefecture on Sunday began health check-ups of 360,000 children amid worries that radiation from a crippled nuclear plant had exposed them to the risk of thyroid abnormalities.

Many parents demanded the tests, drawing parallels with the 1986 Chernobyl nuclear disaster, after which locals reported thyroid disorders, a problem sometimes associated with radiation exposure.

The screenings began after a recent unofficial survey reported that 10 out of 130 children evacuated from Fukushima had hormonal and other irregularities in the thyroid glands.

The doctors who conducted the survey, however, added that they could not establish a link between the irregularities and the nuclear accident.

Officials said they will test some 360,000 children under the age of 18, and will provide follow up tests during their lifetimes.

The March 11 earthquake triggered a tsunami that tore into Japan's northeast coast, leaving 20,000 people dead or missing, while sparking meltdowns and explosions at the Fukushima Daiichi nuclear power plant.

It was the world's worst nuclear accident since the Chernobyl disaster.

Radiation fears are a daily fact of life with reported cases of contaminated water, beef, vegetables, tea and seafood due to the Fukushima crisis.