A survey of European seizures of cannabis resin shows its potency has increased significantly in the ten years from 2006 to 2016.
In Ireland the strength of cannabis has doubled in that time.
That has led to a rise in the number of young people looking for treatment for addiction and psychosis.
The Irish Times reports Ireland has seen a consistent rise in cannabis users entering drug rehabilitation since 2007.
Latest research shows the increase in strength a response by Moroccan producers who have been squeezed out of the market and are looking for a way to increase their share.
The European wide study is contained in the journal Addiction.