Soca, which was billed as the UK's answer to the US's FBI when it was set up in 2006, has come under pressure over the past year to prove its worth.
The agency said its activities in the run-up to Christmas stopped 10 tonnes of street-quality cocaine powder being sold in Britain.
But figures obtained by the BBC suggest almost a third, or 31 per cent, of police cocaine seizures are now less than 9% pure, the lowest recorded purity level.
The data, collected by the Forensic Science Service (FSS), suggests drug gangs are using more and more chemicals to increase the drug's availability on the UK's streets.
Dealers cut with bicarbonate of soda or Creatine. Pure cocaine does not make your nose smart, and some dealers who sell high end stuff add a little ground up aspirin to make customers happy. In a pub, on a night out, 9-15% cocaine would make most occasional users perfectly happy.
What weedkiller are they talking about.
This is a bullshit news story.
Cocaine can destroy your life. And it makes many people really boring. And it makes it hard to get an errection. And if you take it too long you will begin to hallucinate and have paranoid delusions.
But all this is true of alcohol. I think cocaine should be made legally available, with all due health warnings.