The Green party's former science and technology spokesman is promoting anti-radiation pills to people in Japan affected by the Fukushima nuclear disaster, that leading scientists have condemned as "useless".

Dr Christopher Busby, a visiting professor at the University of Ulster, is championing a series of expensive products and services which, he claims, will protect people in Japan from the effects of radiation. Among them are mineral supplements on sale for ￥5,800 (£48) a bottle, urine tests for radioactive contaminants for ￥98,000 (£808) and food tests for ￥108,000 (£891).

The tests are provided by Busby Laboratories and promoted through a body called the Christopher Busby Foundation for the Children of Fukushima (CBFCF). Both the pills and the tests are sold through a website in California called 4u-detox.com, run by a man called James Ryan.

Though a controversial figure, Busby has been championed by the anti-nuclear movement and some environmentalists. He is still consulted by the Green party on issues such as low-level radiation and depleted uranium, but when contacted by the Guardian the party distanced itself from Busy's activities. Penny Kemp, the Green party communications director, said that the party did not condone Busby's promotion of the products.

In a video on YouTube, Busby says that the calcium and magnesium pills will be supplied "at the cost of production". But the prices being charged by 4u-detox.com are far greater than those of other mineral supplements on sale in Japan. Chemists in Tokyo sell bottles of 200 pills containing similar combinations of ingredients for ￥1,029 (£8.49). James Ryan's website also charges a minimum shipping cost of ￥2,300 (£19).

The Japanese government already monitors human exposure to radiation and tests food and water, banning contaminated products from sale. It works to stricter radiation limits than the EU.

Fukushima prefecture has launched a comprehensive radiation testing programme, as well as distributing radiation monitors to 280,000 children at elementary and junior high schools. Hospitals at the edge of the exclusion zone are offering full body radiation scans and the government plans to check the thyroid glands of 360,000 children by March 2014 — with follow up tests continuing for the rest of their lives.

The CBFCF also solicits donations from the public, to be paid into an account called Green Audit at a bank in Busby's home town of Aberystwyth. Green Audit is an environmental consultancy and research organisation founded by Busby.

Launching the products and tests, Busby warns in his video of a public health catastrophe in Japan caused by the Fukushima explosions, and claims that radioactive caesium will destroy the heart muscles of Japanese children.

He also alleges that the Japanese government is trucking radioactive material from the Fukushima site all over Japan, in order to "increase the cancer rate in the whole of Japan so that there will be no control group" of children unaffected by the disaster, in order to help the Japanese government prevent potential lawsuits from people whose health may have been affected by the radiation. The pills, he claims, will stop radioactive contaminants attaching themselves to the DNA of Japanese children.

But Gerry Thomas, professor of molecular pathology at the department of surgery and cancer at Imperial College, London, describes his statements about heart disease caused by caesium as "ludicrous". She says that radioactive elements do not bind to DNA. "This shows how little he understands about basic radiobiology." Of the products and services being offered, she says, "none of these are useful at all. Dr Busby should be ashamed of himself."

Professor Ohtsura Niwa, a member of the International Commission on Radiological Protection, said that Busby had offered no evidence for his claims of deliberate contamination. "It is not possible for the government and Tepco [the company that runs the Fukushima nuclear plant] to cheat people, now that so many citizens equipped with dosimeters are measuring radiation levels all over Japan," he said.

Niwa described Busby's faith in magnesium and calcium supplements for guarding against radionuclides such as strontium, uranium and plutonium as "baseless".

A Japanese government spokesman also rebutted the accusation of deliberately contaminating other parts of Japan. Noriyuki Shikata, deputy cabinet secretary for public affairs in the prime minister's office, said that so far only tsunami debris from Miyako in Iwate prefecture has been transported to Tokyo for incineration, adding that the disposal of waste generated by the disaster applies only to Iwate and Miyagi prefectures, not Fukushima.

"At this point, there are no plans to transport radioactive waste outside Fukushima prefecture," Shikata said. "Efforts are now being co-ordinated to construct intermediate storage facilities for radioactive waste inside Fukushima prefecture."

Yasuhito Sasaki, executive director of the Japan Radioisotope Association, described the idea that large swaths of the country were being deliberately contaminated as "ridiculous". "No decision has been made on the final disposal of radioactive waste," he said. "Local governments in Fukushima haven't even approved a government proposal to store it locally on a temporary basis."

Busby told the Guardian that the money from the sales of pills and tests goes to the CBFCF, which was established by James Ryan. When asked what his involvement with the foundation is, Busby said: "It's got nothing to do with me. He phoned me up and asked if he could use my name and I said he could." But he added: "I'm conducting the tests. I promised him I would measure the samples he sent to me." Asked if Busby Laboratories was his operation, he said, "I'm Busby Laboratories."

Ryan did not respond to a question from the Guardian on why the products and services provided by 4u-detox.com are so expensive. Nor did he provide any evidence for the efficacy of the products when asked.

He did say: "All money from 4u Detox goes to children of Fukushima and children throughout Japan. We have donated a great amount to children of Japan".

Products and services offered by Busby Laboratories and sold through 4u-detox.com

Testing urine for uranium and strontium: ￥98,000 (£808)

Testing food for caesium and iodine: ￥29,800 (£246)

Testing food for plutonium, uranium and strontium: ￥108,000 (£891)

Testing water for caesium and strontium: ￥59,800 (£493)

Russian-made radiation monitors: ￥28,000 yen + ￥3,200 yen for shipping (£257 in total). The same model is available on eBay for £170, including shipping costs.