Met chief attacked by top prosecutor over calls for caught-on-camera drug-taking celebrities to be put on trial

Sir Ian Blair was publicly rebuked by the country's top prosecutor after calling for celebrities caught snorting drugs on camera to be put on trial.

The Metropolitan Police Commissioner said jurors should be given the chance to decide if illegal substances have been taken.

But his comments were immediately attacked by the Director of Public Prosecutions, Sir Ken Macdonald, QC, who said Sir Ian appeared to have 'completely misunderstood the law'.

The row followed a series of controversies involving celebrities who have escaped charges, despite video evidence suggesting they had taken drugs.

Model Kate Moss and singer Amy Winehouse have both avoided prosecution because police could not prove what substance they were taking.

Bob Geldof's daughter Peaches, 19, caught on video apparently buying a banned substance, is likely to avoid charges because of the same loophole.

On his first day as head of Scotland Yard three years ago Sir Ian vowed to crack down on middle-class drug users.

Sir Ian has made great efforts to stay out of the spotlight following a series of high-profile gaffes and has upset the legal establishment before.

Two years ago he nearly lost his job after it emerged he secretly recorded a telephone conversation with the then Attorney General, Lord Goldsmith. He incurred the wrath of the DPP on Friday after giving his first major newspaper interview for several months.

Speaking of his frustration over the drugs laws, Sir Ian cited the case of Miss Moss, who escaped charges despite being pictured snorting lines of white powder.

Police could not prove the substance she was taking was illegal and not, for example, talcum powder, leading to criticism of the nine-month inquiry.

Amy Winehouse, seen here with white powder around her nose, avoided drugs charges earlier this year

Sir Ian said in an interview with the Evening Standard: 'My position is that a sensible jury would not expect people to be sniffing talcum powder. I expressed my concern over the Kate Moss stories, we did that investigation and we hit the same issue.

'At the moment the law says you must be in possession of a Class A or a Class B to be prosecuted. If you are seen on film then nobody can tell what the substance is.

'I think it is reasonable for a jury to say, "You convince me that you are taking talcum powder" because it is an unusual way to take it.'

Sir Ken Macdonald has said that Sir Ian Blair does not understand the law

Kate Moss: The supermodel avoided prosecution despite allegedly being filmed taking drugs

Sir Ken hit back yesterday. He said: 'I'm extremely surprised by comments attributed to Sir Ian Blair. He appears to have completely misunderstood the law.

'The issue was not whether the white powder that Kate Moss was snorting was cocaine or talcum powder.

'The law required us to prove that it was either a class A drug or a class B drug. We could only base our case on one of these options.

'It was impossible for us to do this since cocaine - a class A drug - and amphetamine - a class B drug - are both white powders.

'The analysis attributed to Sir Ian Blair is therefore completely wide of the mark. Any suggestion that the CPS does not prosecute celebrities is completely untrue.

'We will prosecute when the police provide us with sufficient evidence to do so.'

The row went on last night when a Scotland Yard spokesman said: 'As is clear from his comments the Commissioner understands the current law relating to drugs. He has asked for it to be explored whether there are other options that can be used to put such matters before juries or whether this requires a change in the law.

'The Commissioner has not criticised the CPS, he is reflecting a view of many ordinary people about how the law stands in dealing with what is sometimes apparent and obvious drug use.'

Last night, it emerged that Sir Ian was advised by officials at the Metropolitan Police Authority not to give the interview in which he made his remarks.

One source said: 'Sadly, Sir Ian doesn't listen to advice. At a time when teenage knife crime is top of the agenda, there was absolutely no need to start a debate on drugs.'

Sir Ian's previous gaffes include questioning publicly why the Soham murders attracted so much coverage in the media.