New Zealand announced plans Monday to ban the use of party pills and fake cannabis – drugs offering so-called legal highs – unless producers can provide clinical evidence that they are safe.

Associate Health Minister Peter Dunne said Monday that current laws are failing, because as soon as regulators ban a synthetic drug, manufacturers alter its formula slightly and re-launch it. Dunne said the new law means the legal highs industry will be over once and for all.

The United Nations Office on Drugs and Crime says global drug abuse has remained stable, with about 4.8 percent of the population aged 15 to 64 using illegal substances. But in its 2011 World Drug Report the UN says demand for substances not under international control – such as synthetic cannabis and party pills – has soared.