Image caption The government has banned more than 200 substances since coming to power

A new review of "legal highs" could lead to sweeping changes to UK drug legislation, the Home Office has said.

Legal highs - officially known as psychoactive substances - are synthetic drugs which can be bought online and sometimes in shops.

The review follows concern drug laws are not flexible enough to tackle them.

Deaths from legal highs in England and Wales almost doubled to 52 last year. The government said it was "determined to clamp down on the reckless trade".

It is estimated that across the EU one new substance a week is being detected.

'Head shops'

Among options the review will consider is legislation modelled on US laws.

Despite being marketed as legal alternatives to banned drugs, users cannot be sure of what they contain and the impact they will have on their health Crime prevention minister Norman Baker

In the US, drugs are automatically banned if they are "substantially similar" to the chemical structure of substances that are already illegal.

The review will also look at whether those who supply legal highs over the internet and in "head shops" should be required to prove substances are safe and are not being used as a drug.

Similar laws have already been introduced in Poland and the Republic of Ireland.

The review panel - which will include police, prosecutors, health experts and local council officials - has been asked to report back in the spring 2014.

Crime prevention minister Norman Baker said: "Despite being marketed as legal alternatives to banned drugs, users cannot be sure of what they contain and the impact they will have on their health.

"Nor can they even be sure that they are legal.

"Our review will consider how current legislation can be better tailored to enable the police and law enforcement officers to combat this dangerous trade and ensure those involved in breaking the law are brought to justice."

Powerful hallucinogen

The review is being launched on the day the government has announced a permanent ban on two party drugs which were previously legal highs.

Hallucinogenic NBOMe - also known as N-Bomb - and the ecstasy-like BenzoFury were banned for a year in June.

Under legislation to be passed next year, NBOMe - a powerful hallucinogen which causes euphoria but can also lead users to feel nauseous and panicky - will be made a class-A substance.

BenzoFury will become a class-B substance.

The government has banned more than 200 substances since coming to power.