Cannabis use among young people has fallen significantly since its controversial reclassification in 2004, according to the latest British Crime Survey figures published today.

The Home Office figures showed the proportion of 16 to 24-year-olds who had used cannabis in the past year fell from 25% when the change in the law was introduced to 21% in 2006/07 - still about 1.3 million users.

The impact of the new "confiscate and warn" policy towards those found with cannabis was also reflected in a 54% rise in the number of cannabis seizures to 117,297, and in the 63,331 formal warnings issued in 2005, according to the figures.

The increasing spread of the homegrown cannabis industry in Britain can be seen in figures showing that police and customs seized 208,357 cannabis plants - 82% of them in groups of less than 50.

In total, police and customs seized 69 tonnes of cannabis, 49 tonnes of which was "traditional" imported resin and 20 tonnes of which was herbal cannabis.

Gordon Brown has ordered a fresh review of the legal status of cannabis after warnings of links between much more potent strains coming on to the market and mental illness.

But the latest figures suggested that the downward trend in cannabis consumption since 1998 - when 28% of 16 to 24-year-olds reported using the drug - had accelerated.

Among all age groups, 10% of people said they had used an illegal drug in the past year - about 3.1 million people. This was the lowest level since the statistics were first published in 1996.

The figures showed cocaine powder use continued to rise, with 2.6% of adults saying they had used it in the past year. Use of ecstasy and heroin remained stable.

For the first time, the BCS survey measured ketamine use in England and Wales and estimated that about 0.3%, or under 100,000, of the adult population had tried it in the past year.