'Legal highs' set to be banned
BZP is often sold as an alternative to Ecstasy
Two so-called "party" drugs and a man-made cannabis substitute will be banned by the end of the year, the Home Office has announced.
At the moment, these "legal highs" are sold openly across the UK and on the internet, but ministers say they are an "emerging threat".
The two drugs, known as BZP and GBL, have been linked to a number of deaths.
Charity DrugScope said law alone was "a blunt instrument" and greater education was needed about the drugs' effects.
To that end, the Home Office said it would begin an awareness campaign in university freshers' weeks in September to highlight the dangers.
BZP, also known as herbal ecstasy, was linked by a coroner in Sheffield to the death of 22-year-old mortgage broker Daniel Backhouse earlier this year.
It is understood that Mr Backhouse had also taken ecstasy.
Hester Stewart, who was 21 and a medical student, died after taking GBL in Brighton. Her parents have campaigned for the substance, known as liquid ecstasy, to be banned.
Both drugs would be classified as Class C, putting them in the same category as amphetamine.
The cannabis substitute - often sold under the name Spice, for about £20 - is made from synthetic chemicals known as cannabinoids which mimic the effects of marijuana. It would be controlled as a Class B drug, alongside cannabis.
The Home Secretary Alan Johnson said he was acting on advice from the government's Advisory Council on the Misuse of Drugs:
He said: "Legal highs are an emerging threat, particularly to young people, and we have a duty to educate them about the dangers.
"There is a perception that many of the so-called legal highs are harmless, however in some cases people can be ingesting dangerous industrial fluids or smoking chemicals that can be even more harmful than cannabis."
BZP and GBL would carry a prison term of up to two years for possession and 14 years for dealing.
GBL is taken as a substitute for the "date rape" drug GHB, which is already outlawed.
The Home Office says the GBL, originally a worming treatment for cattle, can cause serious heart problems, vomiting, anxiety attacks, mood swings and seizures. BZP has been linked to similar conditions.
Martin Barnes, chief executive of DrugScope, said: "While we support the classification of substances such as GBL and BZP, the law alone is a blunt instrument.
Sussex University student Hester Stewart died after taking GBL
"We have concerns that in lumping all these substances together as 'legal highs', the significant differences in the effects and potential harms might be hard for young people to identify.
"It is important that public information and education campaigns are comprehensive and ongoing."
Mr Barnes also said that while cannabis-substitute Spice should be controlled, there were questions over whether it should be a Class C or B drug.
"A review of the Misuse of Drugs Act was promised by the government in January 2006, but was subsequently dropped.
"Given the number of substances being made illegal under the Act with the likely prospect of more to come... it is even more important that the classification system is reviewed."