Trading Standards says it is powerless under the law to deal with shops selling underage teens legal highs after a 17-year-old reportedly bought a haul of them in Stratford.

The Mystical Headshop, in InShops inside the Stratford Centre on Broadway, was the victim of a sting by the Daily Mirror last week in which they took 17-year-old Hannah Rose-Wynter around London to see if she could purchase legal or herbal drugs.

She reportedly bought £93 worth from the shop without being asked to prove her age.

The sale of such substances to juveniles is not strictly illegal as it falls into a grey area of the law.

The Intoxicating Substances Supply Act 1985 makes it a criminal offence to sell to someone under 18 if the shopkeeper “knows or has reasonable cause to believe the substance or its fumes are likely to be inhaled for the purpose of causing intoxication” which is often difficult to prove.

Newham police said the incident was a licensing issue but Newham Trading Standards said there was not enough scope within the law for them to prosecute, adding “We wish we could do more.”

A Newham Council spokesman said: “Crime and anti-social behaviour is totally unacceptable and we will not stand for it here in any shape or form.

“However, in this instance, as the law stands, it is extremely difficult for local authorities like us to enforce. We wish we could do more.

“Where we can take action - for example tackling the illegal sales of alcohol and cigarette to minors by shopkeepers - we are one of the most proactive councils in the country.”

Ian Bayram, the owner of the Mystical Headshop, said the store has tightened up security since the investigation by asking for ID from shoppers who look under 25 as opposed to under 21 as before.

He added: “It is company policy that products like this are not knowingly sold to under 18s and I have taken this failure very seriously.”

While inShops is situated in the Stratford Centre, the mall’s management said it was not responsbile for its sellers.

Andrew Norton, the centre manager, added: “While the shop concerned is not a tenant of the Stratford Centre, these allegations are troubling and I will be talking to the manager of the store about them.”