A scene from Spiked! which will be shown in cinemas

It shows a man chatting up a girl before spiking her drink, with the final shot depicting the girl alone and dishevelled as she staggers out of the bar.

This is followed by a caption saying: "Now rapists don't have to use force to get what they want. Who's watching your drink?"

The film, called Spiked! after the campaign it forms a part of, came about when Suzanne Jones, who directs television commercials, learned how a friend was drugged and raped in north London last year.

Protection measures

The police investigation resulted in an appeal on BBC Crimewatch, but the rapist has yet to be caught.

Campaigners are worried that women are unaware of the potential dangers as well as the measures which they can take to protect themselves.

Ms Jones said: "With such poor knowledge of the dangers of drug rape, people need to be made aware of the ways in which they can protect themselves.

The film warns women to keep a watchful eye on their drinks

"I had the opportunity to help achieve this, which is why I have made Spiked!"

Experts warn that illegal or prescribed drugs are not the only substances rapists use to reduce their victims' resistance.

Alcohol is also commonly used, they say.

Detective Chief Inspector Peter Sturnam, of the Drug Rape Trust, said: "People who are intoxicated can also be vulnerable to sexual assault and other incidents of crime.

"Drug rape is a very serious concern.

"We all need to take care when out socialising, especially when alcohol is involved."

Liquid ecstasy

Statistics suggest drug-assisted rape may be on the rise.

The Metropolitan Police recorded 164 reports of alleged drug-assisted rape in 2001.

In 2002, they received 192 - a rise of 17%.

The Forensic Science Service says it conducts about 450 investigations into alleged drug-assisted rapes across the country every year.

Friends, club staff, and bouncers all have a responsibility to look out for suspicious behaviour Rape Crisis Federation

But the Home Office says this is very likely to be an underestimate of the true number.

The film-makers say many different "rape drugs" are available.

GHB - also known as "liquid ecstasy" - and Rohypnol are among the most common.

The Rape Crisis Federation (RCF) says campaigns to raise awareness of drug- or drink-assisted rape should target the wider population.

Sue Griffiths, of the RCF, told BBC News Online: "It's not just women's responsibility."

"Friends, club staff, and bouncers all have a responsibility to look out for suspicious behaviour."

Tarantino film

Spiked! will be shown on key British and university cinema screens from this month until November.

It will be seen before movies such as Quentin Tarantino's Kill Bill and Young Adam, starring Ewan McGregor.