The Munster Fianna Fail MEP, Mr Brian Crowley, has criticised some members of the Green group at the European Parliament who "have sought in prior times to legalise the use of synthetic drugs in Europe".
He said "such a regressive step would only weaken the European Parliament's ability to fight the drugs problem effectively in Europe.
"And it would suggest to young people that the use of soft drugs is permissible at a time when we do not have the necessary statistics on the side effects of these for the health of people using such drugs."
He said it was clear that the European Monitoring Centre for Drugs and Drug Addiction in Lisbon and the Europol Drugs Unit must intensify efforts in a co-ordinated and structured manner to give member-states the necessary resources and information to defeat international drug trafficking and drug taking in Europe.
As a member of the Social Affairs Committee of the European Parliament, Mr Crowley said he had regularly called on the drugs centre to research extensively the side effects of the use and consumption of soft and synthetic drugs such as LSD and ecstasy.