Legal highs: What are they, where do they come from, and what will the new law do?

The introduction of a blanket ban on "legal highs" represents an attempt to get a grip on a vast and versatile market.

The drugs are designed to mimic the effect of illegal substances such as cannabis, cocaine and ecstasy.

They are produced in bulk in countries such as China and India before being shipped to Europe. In the UK, they are sold openly by websites and so-called "head shops" around the country.

ITV News Political Correspondent Emily Morgan reports:

They are not automatically banned under the Misuse of Drugs Act 1971 because drugs are classified as illegal by their chemical compounds.

In legal highs, this compound is often slightly altered to avoid the ban. They cannot be sold for human consumption but sellers have got round the law by marketing them as incense, salts or plant food.

The government says it has already taken a range of action on the issue, including banning more than 500 new drugs and creating the Forensic Early Warning System to detect substances not seen before in the UK.

But the current system is seen as laborious because it requires officials to assess new legal highs one by one before they can be outlawed.

Often manufacturers will simply produce a new version with a slightly altered chemical make-up which then comes on sale almost immediately after the previous drug is banned.

Figures published earlier this year by the European Monitoring Centre for Drugs and Drug Addiction revealed that two new legal highs are identified in Europe every week.

Some 101 were detected by authorities across the 28 EU member states, plus Turkey and Norway, last year - a rise of 20 or almost a quarter - compared to the 81 recorded in 2013.

Experts have also previously identified the UK as having the largest market for legal highs in the EU.

The government wants to take a more proactive approach so that new psychoactive substances can be identified before they are available for mass consumption.

Calls for tough action on legal highs emerged after they were linked to a number of deaths. Official figures show that there were 120 deaths involving new psychoactive substances in England, Scotland and Wales in 2013.