A group of musicians and MPs has urged the government to allow on-site drug testing at UK festivals to go ahead.
The open letter calls on ministers to “reconsider” the Home Office requirement for a special licence.
It says safety testing “undoubtedly saves lives” and has been happening without these permits since 2014.
The Home Office says its position hasn’t changed and drug testers have needed licences since 2001.
A row over the topic has been brewing since Parklife in Manchester earlier this month.
Boss Sacha Lord said the festival couldn’t test confiscated drugs and warn people of any safety issues this year, despite having done so since 2014.
He accused the Home Office – which is in charge of drugs policy – of doing a “u-turn” when it told him that the event would need a licence for the first time.
Sacha is among the festival industry figures who’ve signed the open letter alongside 31 politicians and musicians Fatboy Slim, Billy Bragg and members of the band Metronomy.
The group, which includes several Tory MPs, say that “blocking” testing is a “disastrous decision”.
They say the licences are expensive to obtain and take more than three months to arrange.
And they say the terms state that drugs must be tested in a permanent building – making it difficult for festivals set up on temporary sites to comply.
Drug testing is widely supported by UK festival organisers.
They say they don’t endorse or encourage drug-taking, but they accept that some festival-goers will do it so testing is a way to reduce harm.
The letter calls on the government to restore “back-of-house” drugs testing – where confiscated substances are checked for strength, contaminants and to make sure they’re not being mis-sold.
If problems are found a warning is circulated to festival-goers.
In most cases, testing in previous years was done by charity The Loop, under agreements with local councils and police.
Glastonbury, which took place over the weekend, told Newsbeat drug testing was going ahead this year through a private company.
And the organiser of Leeds and Reading Festivals also said it plans to provide it this year.
However, BBC Newsbeat’s been told this will happen off-site, in accordance with licence requirements.
The Home Office has repeatedly rejected accusations of a u-turn, and maintains that its policy on testing is clear.
It says: “Our position hasn’t changed. Drug testing providers must have a licence to test for controlled drugs, including at festivals.
“We have consistently made this condition clear, and law enforcement have always had a responsibility to uphold this legal requirement.
“We have not received any applications for drug testing at the major festivals this summer. We continue to keep an open dialogue with any potential applicants.”