Experts have warned that sexual assaults assisted by drugs are a more significant problem than official records suggest.
Experts suggest hospitals need more facilities to detect drugs
The government's Advisory Council on the Misuse of Drugs said it was concerned that two substances linked with sexual assaults were legal.
It said hospitals and police need to do more to detect the drugs.
Last year separate research by police chiefs found evidence of date-rape drugs was over-stated.
But in its report into drug-assisted sexual assault, the council said it had concerns over two types of drugs thought to be used in date-rape attacks.
The first kind were sedatives which altered behaviour or caused memory loss.
The second was a group of chemicals liable to lower inhibitions and increase libido.
The council said there was emerging evidence of the second group of drugs being used in sexual assaults, including gamma-buterolactone and 1,4-butanediol.
These are both used in legal cleaning fluids - but once ingested they have the same effect as a known date-rape drug, Gamma-hydroxy butyrate (GHB).
GHB and Rohypnol, also suspected of use in date-rapes, are both Class C drugs. The council said it would re-examine the legal status of the two drugs named in its report.
Role of alcohol
In its recommendations, the council said it recognised the "very significant role" played by alcohol in sexual assaults - but added that specific action was needed to deal with attackers who also relied on chemicals.
Date-rape style offences should also be recorded separately by the police and appear in the British Crime Survey, said the council.
It also called on police and hospitals to speed up the detection of the drugs because the chemicals can disappear from the body quickly enough to leave no trace of a crime.
In a separate study published in 2006, senior police officers found that date-rape drugs may not be as prevalent as first thought.
It found that many victims of sexual assault may have just been very drunk. Of 120 cases from November 2004 to October 2005, it said 12 were suspected drug-assisted assaults - but none was linked to the date-rape drug Rohypnol.
The council analysed this research in its own report and found that in some cases there were clear delays between an incident and attempts to detect samples.
And in 41 of the 62 instances where alcohol was detected, one or more controlled drugs were also present.
Professor Sir Michael Rawlins, chair of the advisory council, said: "Drug facilitated sexual assault is a particularly disgusting offence that wrecks people's lives. It is a significant but under-reported problem.
"Most drugs used in drug facilitated sexual assault are already controlled under the Misuse of Drugs Act, but we are concerned that two drugs are not currently controlled and will further consider whether they should be classified."
A Home Office spokesman said it welcomed the report - but rejected the call to separately record drug-facilitated sexual assault in crime figures.
"To flag those offences thought to be 'drug facilitated' would be incredibly complex due to the difficulty ascertaining those factors that caused a jury to find the defendant guilty," said a spokesman.