A complementary medicines expert has raised concerns over the effectiveness of a homeopathic remedy said to contain essence of the Berlin Wall.

The Berlin Wall remedy is available via a London-based supplier bearing the Queen’s seal of approval as an alternative medicine.

Producers believe the “spiritual force” that was in the wall is carried in the remedy, said Edzard Ernst, Emeritus Professor of Complementary Medicine at Exeter University.

He writes about the treatment in his new book, classing it as an “exotic remedy”.

Speaking at the Science and Media Centre, Prof Ernst said: “People think that homeopathy is based on natural substances. Berlin Wall shows this is not true.”

Prof Ernst explained that pieces of the Berlin Wall are ground down and mixed with lactose before being diluted multiple times until they are soluble.

The final product does not contain a “single molecule from the wall”, but is believed to contain its essence, Prof Ernst said.

He added: “Homeopaths do not believe it is a pharmacological action, but it is a sort of vital force that is acting.

“So the vital force, the spiritual force that was in the Berlin Wall, the intention that was in the Berlin Wall, is in the remedy.”

Asked whether the idea is that it “brings down walls” between people, he said “yes”.

Prof Ernst said consumers are likely to have read about the remedy online, on social media or through books.

He suggested the belief is that the wall inhibited communication, so if you have a problem with that, the remedy will help.

“It is a truly exotic homeopathy remedy. I bet many homeopaths have never used Berlin Wall, but it exists,” said Prof Ernst, author of Alternative Medicine: A Critical Assessment Of 150 Modalities.

He added: “The lamentable thing is not that shops sell it, the lamentable thing is that people are being misinformed.”

Ainsworths sells the Berlin Wall remedy on its website, costing £4.20 for a 1g vial of lactose tablets, up to £120 for 1,000ml in liquid potency (23% alcohol).

It holds a Royal Warrant from the Queen and the Prince of Wales, who is also patron of the Faculty of Homeopathy.

Ainsworths said it would not be commenting on the matter.