A blanket ban on synthetic legal highs is to be imposed in New Zealand within two weeks, the country’s ministry of health has said.

The 41 identified substances, currently sold in 150 shops across the country, will be made illegal until manufactures can prove they are low risk, Associate Health Minister Peter Dunne said.

The new ban follows regulation introduced last year that took took around 250 other products - the majority of which were synthetic cannabis - off the shelves.

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The Psychoactive Substances Act requires all manufacturers of synthetic drugs to prove that the legal high is low risk. As the government testing regime is not yet in place, the majority were automatically banned.

41 had been able to remain on sale until now due to receiving temporary approval from an expert committee.

Mr Dunne told The New Zealand Herald: “Last Tuesday, Cabinet agreed on a proposal from me to introduce legislation under urgency when Parliament resumes to remove the remaining 41 products from the shelves until such time as their low-level of risk can be proven.

“I think that the reason we didn't include those 41 products initially was that they hadn't been identified as problematic.”

He added: “The public concern of recent weeks has led me to revisit that question and I've been working on the legislation for some time now.

“In effect what this will mean is that there will be no products until such time as the new regime takes effect and they've been able to be tested.”

The New Zealand government's testing regime, expected to be as rigorous as that applied to pharmaceutical drugs, means that it could cost manufacturers of legal highs over $1 million NZD (£500,000) to have each product approved.