The laws will also make it illegal to import these drugs without a licence from the Irish Medicines Board.

Merchants Quay Ireland Director Tony Geoghegan said there is now a large black market in tranquillisers like valium or xanax.

He said many drug users become unknowingly addicted to the benzodiazepine, which are often more difficult to detox from than heroin.

He also added that it is now the norm for drug users to use prescription drugs such as valium on top of heroin.

Speaking on RTÉ's News at One, Mr Geoghegan said he agreed with Dublin Lord Mayor Andrew Montague that the illicit sale of prescription drugs on the streets of the capital now far outstrips the sale of heroin, cannabis and cocaine combined.