Radiation hot spots have been found at the J-Village sports facility in Fukushima where the Tokyo 2020 Olympic torch relay will begin, Greenpeace Japan says.

Key points: Greenpeace says it detected radiation levels 1,775 times higher than prior to the 2011 Fukushima disaster

Greenpeace says it detected radiation levels 1,775 times higher than prior to the 2011 Fukushima disaster The readings suggest anyone staying in the vicinity of J-Village for two or more days could be exposed to more than the yearly natural radiation exposure

The readings suggest anyone staying in the vicinity of J-Village for two or more days could be exposed to more than the yearly natural radiation exposure The Olympic flame is due to arrive from Greece in Japan on March 20

Greenpeace found radiation levels around the recently refurbished venue — which also hosted the Argentina team during the Rugby World Cup earlier this year — were significantly higher than prior to the Fukushima Daiichi nuclear reactor meltdown in 2011.

J-Village, located near the damaged nuclear power plant, is a national soccer training complex which was also used as an operation base during the clean-up of Japan's nuclear disaster.

Greenpeace's survey found radioactivity readings taken at J-Village on October 26 as high as 71 microsieverts per hour at surface level.

People are exposed to natural radiation of 2,000 to 3,000 microsieverts a year, so anyone staying in the vicinity of J-Village for two or more days could be exposed to more than the natural yearly exposure.

The radiation, although not life threatening for those exposed to it for a short time, is 1,775 times higher than prior to the March 2011 disaster following the earthquake and tsunami, according to the non-government organisation.

The Olympic flame is due to arrive from Greece in Japan on March 20, with the torch relay officially starting from J-Village on March 26.

Risk of heavy rain spreading contamination: Greenpeace

J-Village was used as an operation base during the nuclear power clean-up. ( Reuters )

Greenpeace said in a statement it had sent its findings to Japan's Ministry of Environment, but had not received a response.

"There is a risk that heavy rain will spread these higher levels of contamination on public roads, and re-contaminate already decontaminated surfaces," Greenpeace nuclear specialist Shaun Burnie said.

A ministry official who did not want to be named told Reuters the ministry had been alerted to higher radiation level readings in the area and decontamination measures had been taken.

"The ministry cooperated with related groups to decrease radiation levels in that area," the official said.

"On December 3, Tokyo Electric Power took measures to decrease radiation levels in said area."

South Korea Olympic team to bring radiation detectors

Greenpeace found radiation levels much higher than prior to the 2011 nuclear reactor meltdown. ( Reuters )

Worries that local food could be contaminated by the nuclear disaster have prompted plans by South Korea's Olympic Committee (KSOC) to buy radiation detectors and ship homegrown ingredients to Japan for its athletes at the Tokyo Games.

The KSOC plans to ship red pepper paste, a key ingredient in Korean dishes, and check for radiation in meat and vegetables that can only be sourced locally due to stringent quarantine rules, according to a KSOC meal plan report.

The Fukushima Daiichi nuclear station, located about 220km north-east of Tokyo, was rocked by a magnitude 9.0 earthquake and subsequent tsunami in March 2011, sparking three reactor meltdowns.

More than 160,000 residents fled nearby towns in the aftermath as radiation from the reactors contaminated water, food and air.

Greenpeace called on the Japanese Government to conduct more extensive radiation surveys in the area. It plans to return to J-Village soon to "determine if subsequent decontamination attempts have been adequately conducted".

Tokyo 2020 organisers could not be immediately reached for comment.

Reuters