The government's drug advisers are to consider next week whether to ban Spice Gold, a herbal smoking mixture that is as strong as some strains of skunk cannabis, and other "legal highs".

Spice is sold on the internet and in "head shops" as a herbal high and a nicotine-free smoke, and even advertised as an "aromatic potpourri". It comes packaged in small sealed pouches holding 3g (less than an eighth of an ounce).

But the former head of the Forensic Science Service's drugs intelligence unit, Les King, yesterday told a European drugs conference in Lisbon: "Just a few months ago, it was found that a smoking mixture known as Spice was not the innocuous material it purported to be. The claimed constituents, namely various herbs, were a Trojan horse."

He said that the substance's real psychoactive constituents were synthetic additives, such as ones that mimic the effects of some of the more powerful active ingredients in cannabis.

King told the European Monitoring Centre for Drugs and Drug Addiction conference that the Spice Gold smoking mixture had been imported first from China and had been around since 2006. It mostly contained an unidentified herbal matter, sold at about £15.50 for 3g and produced a "cannabis-like" effect. There was also a more powerful type, Spice Diamond, on the market, and similar substances were sold as Yucatan Fire.

King is to give a presentation next week in London to the Advisory Council on the Misuse of Drugs, where his colleagues will debate whether to recommend that Spice be banned in Britain.

The move follows a request from the home secretary, Jacqui Smith, to look at the availability and harmfulness of a series of "legal highs" including the herb Salvia divinorum, commonly referred to as magic mint or Mexican sage, which has a naturally occurring psychoactive ingredient. But the advisory council, of which King is a member, will consider Spice first.

The "Trojan horse" properties of Spice were identified only last December by the THC Pharma laboratory in Germany, which is developing medicinal cannabis as synthetic imitations of the plant's active ingredients. Its research led to Germany and Austria banning Spice in January this year. France decided to take the same action in February.

The first batches of Spice were seized in 2006 in Sweden and Jersey, but analysis failed to find any banned substances within them. Early last year the European monitoring centre's early warning system, which links police, customs officials and drug specialists around the EU, identified a dozen online distributors – half based in Britain and a third in the Netherlands – who were promoting Spice.

King, in a paper entitled New Drugs Coming Our Way delivered to the monitoring centre's conference, said that many "designer drugs" had been discovered across the EU since the early 1990s. These were psychotropic substances related to amphetamine and MDMA, the active ingredient in ecstasy, and were predominantly stimulants or hallucinogens. As some of the drugs were banned in some EU states but not others, new law enforcement problems arose until a European-wide "joint action" on new synthetic drugs was developed in 1997 and expanded in 2005.

"The term 'new' referred to 'newly misused' as in almost all cases the substances had been first synthesised many years ago, often as potential therapeutic agents," said King. "Since 1997, over 80 substances have been reported via the early warning system."

He added that in the past few years a much more diverse range of substances had appeared, many of them MDMA-like, or stimulants, or, less commonly, hallucinogens. They included plant products such as Hawaiian Baby Woodrose, Kava and Kratom, unusual stimulants, ecstasy-style drugs such as BZP, which is now banned in four EU countries, and misused medicinal products. They even included Fluorotropacocaine, the first designer drug based on cocaine.

King, who is the UK correspondent for the EU's early warning system for new drugs, predicted that synthetic drugs would continue to dominate the "legal highs" market and that herbal products would remain relatively uncommon. He suggested the emergence of these novel substances raised questions about how well placed the European authorities were to detect them. "Event the best-equipped labor­atories in the EU can struggle to identify new substances, particularly if, as so often happens, neither pure reference mat­erials nor analytical data are available. We must ask whether we are forever doomed to be reactive. Can new substances be anticipated?"

He told delegates the answer to his question was that it should be possible to anticipate new substances given a knowledge of the literature and the use of rules.

• This article was amended on Thursday 17 September 2009. We said that 3g was less than an ounce. 3g is in fact less than an eighth of an ounce. This has been corrected.