Controversial plans to downgrade ecstasy to a class B drug will be the subject of fierce debate on Tuesday, when the Advisory Council on the Misuse of Drugs (ACMD) is presented with evidence on why the drug should remain class A.

The ACMD's new chairman, Professor David Nutt, published a report in 'The Lancet' last year that ranked the drug as less harmful than alcohol and tobacco. But Professor Andy Parrott of Swansea University argues that it is at least as powerful as cocaine.

Writing in the latest issue of 'Addiction Today', Professor Parrott accuses the ACMD of proposing to downgrade ecstasy "without a full and very detailed consideration of the extensive scientific evidence on its damaging effects."