At least 700 people working in the nuclear industy in Japan may have died from exposure to dangerous levels of radioactivity.

The incident at the Tokaimura plant one month ago has revealed dangerous practices likened by some critics to "modern slavery" within the industry, putting the lives of untrained temporary workers at risk.

Juliet Hindell: Workers want explanations

Employment brokers are recruiting temporary workers from Japan's growing number of homeless people to do jobs like cleaning nuclear reactors.

The recent poor safety record of the industry has made it hard for them to recruit staff, but the homeless are tempted by promises of much higher wages than other jobs can offer.

It is thought that 5,000 people a year are employed on a short-term basis.

homeless people are recruited for dangerous jobs

Matsumoto-san, a homeless man living in a park in Tokyo, did a cleaning job for three months at a nuclear plant in Tokaimura near to where the accident took place. He says he was exposed to dangerous conditions: "We were sweeping up dust and had bleepers which went off when the radiation levels were too high, but the supervisors told us not to worry, even though they were bleeping. I got out when I started to feel ill."

The company where Matsumoto-san worked has refused to pay compensation, saying there was no proof his illness was work related.

Many workers get only superficial safety training and have no idea how dangerous their jobs are, according to insiders throughout the industry.

Few have access to medical care or information.

The internationally recognized safe level of radiation since 1990 has been 20 milli-sieverts per year, but Japan has never adopted this standard.

"Modern slavery"

Some homeless workers say they do a shift at one nuclear plant and then work more hours in the same day at another one to earn more money - exposing themselves to more radiation.

Professor Fujita tries to warn people

Yukoo Fujita, a professor of physics at Keio University has tried to warn temporary workers by putting up posters outside plants, and helps people who later fall sick. He describes their employment as "a modern form of slavery".

The Japan Atomic Power company however is adamant that safety standards are adequate. Hideaki Yamakawa, an executive at the company, says they follow government regulations and record the amount of radiation exposure of everyone who works at the plant.

He admits however that "cleaning and such activities are delegated to sub-contractors so we don't know what their hiring policy is."

The use of temporary workers in nuclear plants is regarded as a sensitive issue and has not been widely reported in Japan. Many are too frightened to speak because gangsters are involved in recruiting the homeless.