The use of traditional drugs such as heroin is falling, but new, often toxic “legal highs” are appearing at a record rate of two per week, according to a new report.

A total of 101 new psychoactive substances were detected in the European Union last year, up from 81 in 2013.

That means the EU drugs agency, based in Lisbon, is now tracking more than 450 legal highs — more than half of them identified in the last three years.

The highest levels of legal high use in the last year were reported by young people from Ireland, coming in at 9%.