Stemedica president Nikolai Tankovich was a key player behind a bottled water which hit controversy in the UK over claims it was chemically unique.

Penta's website describes the product as the "cleanest known bottled water — hundreds of times cleaner than many of the bottled spring waters".

However, it stopped trading in the UK shortly after the British Advertising Standards Authority asked bosses not to repeat claims that it had health benefits above ordinary water, according to leading UK newspaper The Guardian.

Penta — manufactured by Bio-Hydration Research Lab, for whom Dr. Tankovich is listed as a director — was also involved in a row played out in The Guardian.

Guardian journalist Ben Goldman, who attacked Penta's claims in his Bad Science column, said he later received a text message from the company warning: "Goldmember I do hope you are a better physician than you are a journalist when we publish you will of course be informed out of the decency/courtesy you didn't show to us! Sleep well tonight and think about how and why you tried to f*** us over and practice keeping one eye open."

Mr. Goldman said Penta later apologised.

Penta is still selling elsewhere and its website contains this statement of endorsement from rock star Sting: "Penta is a perfectly tuned instrument of superior purity, taste and hydration.

"There are lots of great waters out there, but none of them hydrate me like Penta does. With Penta, water isn't 'just water'. Penta Rocks!"