A Harpenden entrepreneur is at risk of his start-up fitness app, Gymster, being ruined by frauds on Twitter who are using his brand to promote dangerous health supplements.

Mark Runza quit his job as a visual architect in London last year to develop, build and promote his fitness app, which he says “randomises exercises based on the equipment available”.

More then 7,000 people have downloaded the app and it has seen endorsements from various fitness-related social media accounts and from personal trainers across the county.

However, the 29-year-old Gymster CEO has seen fake accounts open on Twitter using his company’s logo alongside a tweaked version of the Twitter handle.

Mark said: “Anyone with half a brain cell can see they’re fake but the whole ethos of the company is the exact opposite of what these people are trying to sell.”

Testosterone supplements, steroids and bogus herbal teas have been advertised on the fake Twitter accounts and although it is not clear how many people have fallen for the scam, Mark is keen for Twitter to ‘verify’ his account.

Verification on Twitter stamps an account with a tick assuring followers that an account is genuine.

Celebrities, businesses and public figures are keen to acquire verification in response to fake accounts, but the process can be frustrating.

Mark said: “I’ve had absolutely no response from Twitter. It’s alright for big businesses because they have the power to get verification whenever they want. For start-ups like mine, it’s near impossible.”

Click here or search for Gymster on the Apple app store or Android market.