Party pills on sale in Auckland are made with an experimental substance virtually unknown to scientists worldwide.
The London Underground "Neuro Blast" pills were withdrawn from sale this week after a Weekend Herald investigation revealed they contained the potentially illegal substance diphenyl prolinol.
But further testing by theInstitute of Environmental Science and Research (ESR) has found the "Head Candy" pills from the same range - still available in the city yesterday - also contain the substance.
The pills, marketed as "next generation" and "non-BZP", are designed to side-step the Government's imminent ban on BZP.
The Weekend Herald sent both pills to the ESR for testing this week.
It showed they contained diphenyl prolinol, which the ESR believes is a potential analogue of the Class C5 drug pipradrol, a stimulant with side-effects ranging from insomnia to psychosis and convulsions.
If proven, this would make it illegal to possess, sell or manufacture.
ESR forensic programmes manager Dr Keith Bedford said virtually nothing was known of diphenyl prolinol.
"We have essentially come up with next to nothing on the effects or hazards or risks associated with it.
"There has been virtually no testing that we can identify."
Police were first alerted to the potential illegality of the Neuro Blast pills by the Ministry of Health in late September. They notified London Underground but followed that up only last Friday with a visit by officers.
The Head Candy pills had not been tested before this week, but police yesterday said they would act on the findings.
London Underground owner Chris Chase said he believed all the pills had been withdrawn from sale, and the Head Candy must have been "existing stock" held by a shop.
He said the ESR finding that diphenyl prolinol was a controlled drug analogue was debatable, and he was seeking a court hearing to decide.
The Government aims to ban BZP by Christmas, with a law change making it a class-C controlled drug.
A legal loophole means party-pill makers can sell products without having to prove their safety.
Associate Health Minister Jim Anderton is aware of the loophole, but says it will not be addressed until after a Law Commission review of the 30-year-old Misuse of Drugs Act scheduled for some time next year.
National Party health spokeswoman Jacqui Dean called for the loophole to be closed immediately.
