Gordon Brown' s promise of an immediate ban on the so-called legal high mephedrone was last night undermined by an EU directive.
Critics say that any delays mean more young people will die from taking a drug they mistakenly consider to be safe.
The Prime Minister yesterday said the Government was 'determined to act to prevent this evil hurting the young people of this country', following a string of deaths linked to mephedrone, also known as meow meow.
But the UK Independence Party last night dealt a blow to Mr Brown's announcement with the unearthing of an EU directive which will significantly slow down the move.
Under the EU Technical Standards and Regulations Directive 98/34/EC, the Government has to give the
EU at least three months' notification before it can change British legislation.
UKIP spokesman Nigel Farage said: 'The Government is kidding the people but it simply can't act without an EU-enforced delay.
'This useless government needs to tell the EU to back off from controlling or delaying British legislation.'
Mr Brown said: 'The advice is clear that just because the substance is legal, it doesn't make it safe.
'But we are very concerned specifically about the harms of mephedrone, and the Advisory Council on the Misuse of Drugs is considering this as an absolute priority.'
Professor Les Iversen, the Government's chief drugs adviser, has indicated that mephedrone is likely to be made a Class B drug.
By James Slack
March 25, 2010
Ban on meow meow to be delayed by EU