It is colourless, odourless and tasteless. It is bought illegally in liquid or capsule powder form and if slipped into your drink it can cause you to feel both elated and sedated.

It has become the drug of choice for would-be rapists.

GHB - gammahydroxybutyric - is a sedative that also produces feelings of euphoria. Originally developed as a medicine for use during surgery, it is similar to a chemical called gamma amino butyric acid which occurs naturally in the brain.

GHB, or liquid ecstasy, is known as a party drug' but has also been linked to date rape. In small doses it acts as an upper' and has been taken by clubbers to intensify the effects of alcohol and act as an aphrodisiac.

But in larger amounts the drug can produce an anaesthetic effect. When the colourless, odourless liquid is used to spike drinks it leaves the mostly female victims with hazy recollections of what happened to them and of their attacker.

GHB was outlawed in 2003 and made a Class C drug. Dealers in the drug face up to five years in prison, and possession carries sentences of up to two years.

The issue of date rape drugs hit the headlines yesterday when singer Chenai Zinyuku pulled out of Bingley's Party in the Park on Sunday after it was claimed her drink was spiked the previous night.

Chenai, a runner-up on last year's series of The X Factor, spent the early hours of Sunday in hospital and the rest of the day in bed after falling ill during a night out in Leeds.

Her publicist Adam Muddle told the Telegraph & Argus: "On a night out with friends Chenai had her drink spiked with what is thought to be the date rape' drug GHB and is now recuperating at home."

Chenai had a lucky escape. Campaigners say hundreds of women are raped each year after their drink or food is spiked with GHB and other drugs like Rohypnol.

But a spokeswoman for Bradford Rape Crisis said it was difficult to gauge how many cases of drug rape there have been recently because police statistics don't break down cases in this way.

The spokeswoman said: "Women need to be aware of the issue and aware of what they are doing on a night out.

"The reality is that a lot of women are raped by men known to them and that applies to drug rape as much as anything else.

"We all know that on a night out we can end up doing things that may be irresponsible but I don't want to tell women that they can't go out or that they must take responsibility for the actions of men. I would advise women to have an agreement with trusted friends before they go out, even if it means one of the party not drinking. Women must be aware of the reality and make choices accordingly."

Rape Crisis believe women are not responsible for rape of any kind.

"So-called drug rape' is a media label in response to attacks on women and girls that have happened in the UK over the last ten years in incidences where drugs have been given to women, unwittingly, in a social setting by a man known or unknown to them. The drugs have been usually delivered' through drink, either alcoholic or non-alcoholic.

"It is important to point out that reactions vary from person to person and depend on which type of drug was used. Drugs used may result in a woman becoming physically helpless' to respond, resulting in loss of memory (which may or may not return) or may stimulate sexual response. Women are not to blame for any of this.

"Even if she consented to take the drug a woman is still not responsible for any subsequent abuse. Women may experience extreme fearfulness or an out-of-control' sensation, particularly if they can't remember what happened. Women may have suffered physical injury but be unaware of it immediately or of how the injury happened. As well as this, women experience the same harms in drug rape as for any other rape, such as risk of disease and pregnancy."

Last year West Yorkshire Police joined forces with pub operator Mitchells & Butlers and Arriva buses in an initiative to raise awareness of drink-spiking and drug rape, and of the steps people can take to reduce the chances of becoming a victim. Bars in Wakefield were provided with posters and T-shirts for staff to wear and special tags were placed over the necks of bottled drinks. Police were out and about in pubs and clubs talking to revellers and providing them with information on the risks associated with unattended drinks.

Chief Inspector Mick Quirk from West Yorkshire Police's community safety department, said: "Fortunately this type of offence is still rare, but we need to ensure that people are aware of the risks and that they take the necessary precautions to prevent it."

The STAR (Surviving Trauma After Rape) Project provides a confidential support service for anyone over 14 in West Yorkshire who has been raped or sexually assaulted. Specially-trained workers provide practical and emotional help for victims in their own homes and further counselling is offered where necessary.

Barbara Sielecki, of the STAR Project, said: "We welcome any initiatives which raise awareness about this most horrible crime and would urge victims to contact us to receive appropriate help and support."

West Yorkshire Police offers the following advice on reducing the chances of becoming a date rape drug victim: l Plan your night out and watch out for your friends l Don't accept drinks from people you don't really know or don't trust implicitly l Never leave your drink unattended, or swap or share drinks l Take your drink back if you notice any change in the colour of it l If you feel too drunk too quickly, tell a trusted friend l If you think you may have been a victim report the matter quickly to the police, a crime reporting centre or a victim support group.

A police spokesman said: "Drugs can quickly leave the body so it is important to take a blood or urine sample as soon as possible. Other forensic evidence, such as clothing, will also need securing as quickly as possible."

Counselling and advice for rape victims is available from a number of groups including the STAR Project on (01924) 298954 or www.starproject.co.uk and Bradford Rape Crisis on (01274) 308270.