The warning came after Guy's and St Thomas' reported its name was being used fraudulently in weight loss social media videos last month.

A King's College spokesperson said: ‘We have been made aware of fraudulent adverts circulating online and on social media promoting weight loss patches. The adverts falsely claim that King's College Hospital NHS Foundation Trust clinicians use or endorse these products. The same adverts also use our trust name and logo without permission.

‘We can confirm these adverts are fraudulent and the people named and pictured are not members of our trust staff. We are working to have the adverts removed and encourage anyone who sees these adverts to report them directly to the platform they appear on.

‘At King's, we do not endorse or promote any commercial products, services, or treatments that require purchase, whether for weight loss or any other healthcare purpose. Our clinical advice is provided through official, free NHS channels.'