Senior police officers have written to a government advisory panel urging it to leave ecstasy as a Class A drug, the BBC has reported.
The Advisory Council on the Misuse of Drugs is meeting to discuss whether or not it should be downgraded to Class B.
Incoming head Prof David Nutt has said ecstasy is less harmful than cocaine or heroin and should be reclassified.
The government oppose a change and went against a recommendation in May and moved cannabis from Class C to B.
BBC home affairs correspondent Danny Shaw said the meeting over ecstasy "could set the government on another collision course with the Advisory Council, should it recommend reclassification".
The panel will review the latest evidence before making its decision.
As part of the discussions, panel members will consider the submission from the Association of Chief Police Officers, stating that transferring ecstasy to class B would send out an "unfortunate message".
An estimated 250,000 people in England and Wales take ecstasy every month.
As a Class A drug, the penalties for possession and supply are the most severe.
Possession carries a maximum sentence of up to seven years in prison, an unlimited fine or both.
Dealers face a maximum jail term of life imprisonment, an unlimited fine or both.
Possession of Class B drugs carries a maximum prison sentence of five years, while dealing can attract a term of up to 14 years.
The Home Office has said ecstasy should stay in class A because there is no such thing as a "safe dose".
In May, Home Secretary Jacqui Smith announced plans to reclassify Cannabis as a Class B drug.
This was despite the council stating it should remain as Class C.
