GARDAI have swooped on head shops around the country warning owners they are breaking the law by selling psychoactive substances.
The vast majority of the stores stocking the drugs have now closed, though some remain open selling pipes, bongs and other paraphernalia.
The closures came after Health Minister Mary Harney announced a ban under the Misuse of Drugs Act 1977, through a Government order, on drugs being sold as 'legal highs'.
The banned substances include synthetic cannabinoids, benzylpiperazine, mephedrone and piperazine derivatives.
In addition, the Government is to draft legislation regulating the sale of drugs that may have psychoactive effects.
As a result of the Cabinet-approved order, it is an offence to import, export, produce, supply or possess the prohibited substances where they are to be used for human ingestion.
The exception is when they are intended as flavouring in food.
Well-known head shop chain Nirvana, which has six branches, cleared its shelves of the formerly legal highs.
A note in the window of the Dublin Head Shop in Temple Bar apologised to customers for the closure. Gardai carried out a series of visits to the 102 head shops around the country following the Cabinet's decision.
It is understood a significant number of store owners handed over the banned products when gardai arrived.
By today, officers had made contact with all owners to make them aware of the new legislation.
Ms Harney said possession and supply of the listed substances was now illegal.
Anyone convicted of unlawful possession faces up to seven years' imprisonment and a fine, while suppliers could be jailed for life, she added.
"This means that the reckless, irresponsible people, who have sold and promoted them must safely dispose of every product containing even one of the substances immediately," the minister said.
Manufacturers of the drugs are expected to attempt to try to get around the ban by changing the components of the substances.
However, Justice Minister Dermot Ahern is expected to introduce the new Criminal Law (Psychoactive Substances) Bill 2010 before the summer break.
It will give gardai powers to close the shops, with the onus being placed on proprietors to then prove they were not selling illegal drugs.