LISBON, Portugal (AP) — The European Union’s drug agency says new psychoactive substances continue to proliferate across the continent, with their volume, diversity and availability placing authorities under increasing pressure.

The annual European Drug Report published Tuesday said the agency identified more than 80 new chemical drugs last year, making a total of almost 250 detected over the past four years.

The new substances are not controlled under international law. They are widely sold as “legal highs,” often over the Internet, and try to mimic the effects of controlled drugs such as cocaine or LSD. While some are manufactured in clandestine European laboratories, they are more often imported from China and India.

The Lisbon, Portugal-based agency said the use of established drugs such as heroin, cocaine and cannabis is broadly stable or in decline.

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