A company that produces an electromagnetic pulse machine has dismissed claims from entertainer Noel Edmonds that it "tackles cancer".
EMP Pad said it did not agree with comments he made on Twitter "in any way, shape or form".
The Deal Or No Deal presenter said it was "a simple box that slows ageing, reduces pain... and tackles cancer".
In response to one cancer patient's comments, he suggested the disease was caused by "negative attitude".
Earlier the Advertising Standards Authority said it was "urgently looking into" a complaint made over the claims but it has since said no rules were broken.
The Medicines and Healthcare products Regulatory Agency said it was investigating the products available from EMP Pad "to determine whether there are any breaches of the Medical Device Regulations 2002".
Mr Edmonds is a long-time fan of the EMP Pad, a machine which aims to stimulate "cellular resonance" in the body with "low intensity and frequency pulsed electromagnetic fields", and costs £2,315.
Praising the machine, which he has previously called a "miracle pad", he tweeted: "A simple box that slows ageing, reduces pain, lifts depression and stress and tackles cancer. Yep tackles cancer!"
Twitter users were quick to respond to his tweet, including from @VaunEarl, whose Twitter biography states he has kidney cancer, lymph node metastases and psoriatic arthritis.
@VaunEarl tweeted: "I think Noel Edmonds should stick to what he's good at. Presenting quiz shows and beard trimming, rather than curing cancer."
Mr Edmonds responded by tweeting: "Scientific fact-disease is caused by negative energy. Is it possible your ill health is caused by your negative attitude? #explore".
@VaunEarl replied: "Wow! How do you know I have a negative attitude. You have no idea who I am. #patronising #cancer... I'm the most positive person I know despite my disabilities and long term ill health. Weird."
Others mocked Mr Edmonds' claims on social media.
The Advertising Standards Authority said it was aware of concerns about Mr Edmonds's claims but after contacting the company was satisfied that no rules had been broken.
A spokesman said: "They were not aware of and didn't have control of the tweet and as such it's not an ad for the purposes of our rules. We will, however, be reviewing marketing claims on EMP Pad's own website to ensure they are sticking to the strict medical devices advertising rules that are in place."
EMP Pad Limited said it did not pay Noel Edmonds to advertise the product. Company director Maria Robertson said she had known Mr Edmonds for over 25 years and had previously worked for him and his daughter Charlotte.
Its directors published a statement which said: "The opinions of Mr Noel Edmonds are his alone and do not reflect in any way with the opinions of us at EMP Pad.
"We had no discussion, input or prior knowledge of the content of Mr Edmonds' statement and we do not agree with it in any way, shape or form."
The company added that its devices use "very low intensity and frequency pulsed electromagnetic fields (PEMF) which target the cells within the body and help to improve the way they function".
It added: "Although research using very low frequency and intensity PEMF to help address cancer has produced some promising early results, it is currently in the very early stages and EMP Pad does not make the claim that PEMF therapy can prevent cancer."