Organisers of this summer's music festivals have been asked by the government to warn revellers about "legal highs".
Minister for Crime Prevention, James Brokenshire, wrote to festival organisers asking them to warn people how such substances could be dangerous.
He said drug laws would be changed and a temporary ban may be introduced while "full scientific advice" was sought.
Letters were also sent to councils and police forces in festival areas.
Mr Brokenshire said: "During the festival season we know that people may be tempted to try potentially dangerous new drugs, particularly when they are advertised as 'legal' or 'herbal'.
"That is why we are asking festival organisers and police to work with us to send out the message that these substances may not be safe and could contain illegal drugs.
"We are going to change our drug laws so we can respond quickly to emerging substances by introducing a temporary ban while we seek full scientific advice."
'Protect the public'
Some drugs previously sold as "legal highs" have now been banned, including mephedrone, now a Class B drug.
The Home Office said that the drug naphyrone is branded as NRG1 and sold as "plant food" or "bath salts", but may contain one or more illegal drugs.
The government said it will not permanently ban a substance without receiving full advice from the Advisory Council on the Misuse of Drugs.
In the letter sent to festival organisers, Mr Brokenshire said: "As part of your preparations for this year's event I ask you to review the measures you have put in place to ensure that your festival is as safe an environment as possible, to help protect the public, especially young people from the potential harms and risks of all drugs."
The government's advice has been welcomed by Melvin Benn, managing director of Festival Republic, which stages the Latitude, Big Chill and Reading and Leeds Festivals.
He said: "I can confirm that we do not allow legal high traders to trade at any Festival Republic festival and fully support the minister's view." http://news.bbc.co.uk/1/hi/uk/10359383.stm
Above is a lesson in how to waste money. isn't it nice how much my government cares about my well being? you know if they really were concerned about dangerous life threatening chemicals maybe they should start by banning tobbaco and alcohol then they should look at food additives like aspertame and the flouride in my water supply. all of which are just as toxic as anything they're trying to ban. Our drug laws are there to protect the profits of the corporations not the health of the people.pathetic.