The Government and police are failing to get to grips with an "epidemic" of so-called legal highs and an overhaul of legislation is needed, a cross-party parliamentary committee has warned.
The Home Affairs Select Committee said chief constables and other law enforcement agencies are failing to understand the impact of psychoactive substances, otherwise known as legal highs.
The group of MPs said the Government has been "unacceptably slow" in setting up an effective legislative response to the problem. And the Committee has recommended a model in which the burden of proof is taken from law enforcement authorities and placed on those who are selling legal highs - similar to an approach seen in New Zealand.
Keith Vaz MP, chair of the Committee, said: "We are facing an epidemic of psychoactive substances in the UK with deaths increasing by 79% in the last year. New versions of these 'legal highs' are being produced at the rate of at least one a week, yet it has taking the Government a year to produce five pages of guidance on the use of alternative legislation.
"This slow response to the crisis may have led to more deaths. Those who sell these killer substances need to be held responsible. New laws should be enacted to put the onus on them. Especially at this time of year, young people need to take care about what substances they consume so their health and lives are not put at risk."
Legislation needs to allow sellers of legal highs to be prosecuted for an offence equal to those under the Misuse of Drugs Act. Deaths involving legal highs such as mephedrone increased by 79% from 29 in 2011 to 52 in 2012. The Committee heard evidence that they can be found in petrol stations, takeaways, tattoo parlours, newsagents, tobacconists, car boot sales, sex shops, gift shops, market stalls and pet shops.
It also heard consumption of legal highs appears to be higher outside major towns and cities, in areas where it is more difficult to acquire conventional drugs. In its report, the group of MPs said: "Chief constables and other law enforcement agencies are failing to understand the impact of psychoactive substances. We are deeply concerned that there is not enough data collated by each local police area regarding the usage and effect of these types of substances.
"We recommend that police forces start a process of data collection immediately in order to have established, within six months, the challenges they face locally."
The Committee said the Home Office should introduce a new legislative model, taking into account the benefits of other systems in use abroad. The group of MPs also said it was concerned by the length of time it has take the Government to produce guidance on the use of alternative legislation - such as Trading Standards laws.
Diana Johnson, shadow crime and security minister, said: "This report is a shocking indictment of the Tory-led Government's complacency about legal highs. "The number of new drugs, number of users of new drugs and the number of deaths caused by new drugs have all rocketed, and after reading this report David Cameron and Theresa May cannot continue to pretend they have the situation under control. The Government need to adopt both of the Committee's key recommendations - new legislation and better education.
"Labour has called for widespread, evidence-based education programmes to be in schools, but ministers have refused to do this. We have called for new laws to enable prosecutions of sellers of these legal highs."
Danny Kushlick, head of External Affairs at Transform Drug Policy Foundation, said: "Transform welcomes this latest report from the Home Affairs Select Committee as it demonstrates unequivocally the complete failure of successive governments to get drugs under their control and calls for better drug regulation. It is the Government's prohibition of cannabis, ecstasy and cocaine that has led directly to the proliferation of new psychoactive substances.
"But the real 'legal highs' are alcohol and tobacco, which continue to be sold in sweetshops and supermarkets, despite the fact that between them they kill up to one hundred thousand people in the UK each year."
Crime Prevention Minister Norman Baker said: "I reject the suggestion that the coalition Government has been slow to act in addressing the threat posed by so-called 'legal highs'.
"We are determined to clamp down on this reckless trade, which has tragically claimed the lives of far too many young people. The reality is we are ahead of the rest of Europe in combating 'legal highs' and have already banned hundreds of these substances.
"But we are not complacent. Only last week I announced a review to consider how current legislation can be better tailored to help police and law enforcement officers bring law-breakers to justice."