A ban on a range of so-called "legal highs" came into force today.

The ban covers GBL, BZP and man-made chemicals sprayed on herbal smoking products such as "Spice", which are now classed as controlled substances under the Misuse of Drugs Act 1971.

The crackdown comes after the high-profile case of medical student Hester Stewart, 21, who died in Brighton in April after taking GBL.

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But her mother Maryon believes the new rules "do not go far enough" because GBL is only classified as a Class C illegal drug.

She said: "In America, it is schedule A, which is the equivalent of a Class A drug here."

However, Home Secretary Alan Johnson said: "We are sending out a clear message to anyone who is thinking about experimenting with them (the drugs), particularly over the festive period, that not only are they putting themselves in danger, they will also be breaking the law."

Fifteen anabolic steroids are also to be controlled as Class C drugs, alongside two growth promoters.