The Customs Minister says there has been a sharp increase in seizures of fake LSD at the border.
Customs has seized more than 16,000 tabs of fake LSD in the past 18 months, up from just 11 tabs in total in 2011.
The minister, Nicky Wagner, says the tabs don't contain LSD, instead they contain much more dangerous and unpredictable synthetic compounds, or mimics of other drugs such as amphetamine.
She says recent hospitalisations in Christchurch and deaths overseas show how easy it is to overdose on the drugs, which are very potent.
The penalty under the Psychoactive Substances Act for importing LSD mimics is a maximum of two years imprisonment.
Importing LSD has a maximum penalty of life imprisonment.