Home Office figures show the number of people held for drug offences rose by almost a fifth in 1997, from 114,800 to 135,600.

The number jailed for drug crimes also hit a new high, again up nearly 20% to 10,422.

Overall, of people found guilty of drug offences, 9% were jailed, 22% were fined and 50% were cautioned.

Cannabis remains the most commonly-used drug

Cannabis remains overwhelmingly the most common drug in circulation, accounting for 76% of incidents, followed by amphetamines at 12%, heroin and ecstasy-type drugs both at 4%, cocaine at 3%, and LSD just 1%.

Heroin use appears to have soared in recent years, with the number of people arrested in connection with heroin rising almost 50%, from 6,000 to 8,800.

The amount of heroin seized in the same year more than doubled from 1,070kg to an all-time high of 2,235kg. Ten years ago the figure was 236kg.

Campaigners for the legalisation of cannabis said the figures showed how much money was being wasted pursuing people for using the drug.

The International Cannabis Coalition, which is holding a march in London on 1 May to publicise its cause, said it was time for the government to rethink its strategy.