He said: “I don’t want to get to a situation where I have to go to the home secretary every month and ask for something else to be banned.
“It’s a new highly profitable industry. It’s a game between the chemical manufacturers who are obviously quite smart chemists, internet dealers and the law.”
Critics say banning a substance could cause bigger problems.
Michael Linnell, from the drugs charity Lifeline said: “What we’re in danger of is that nobody knows what the law is. You can’t just ban your way out of a problem because it could result in far more dangerous chemicals coming onto the market.
“We’re now in a situation where people are snorting white powder and they have no idea what it is and the people selling it don’t know what it is either.”
Most of the legal highs are manufactured in China and imported to the UK where they are sold as “research chemicals” or plant food. Dealers are able to get round the law by making sure they state substances are not for human consumption.
Experts say MDAI, a synthetic chemical that replicates the effects of ecstasy, will be the next legal high to take off.
In the investigation the BBC bought samples online and had them analysed by Dr John Ramsay, a toxicologist from St George’s, University of London.