The public... thought drugs were being legalised and that wasn't the case

Deputy Assistant Commissioner Mike Fuller

There has also been a 35% increase in the number of instances of possession recorded and an 11% increase in drug trafficking offences recorded.

Critics of the scheme, set up by the Met commander Brian Paddick, say the increase in recorded offences is because drugs have flooded into the area as a result of the experiment.

Senior officers admit that what appears to work in Lambeth might not be the case in other parts of London.

Sir John said the results of a MORI poll show that attitudes to the scheme are split along racial lines in Lambeth.

'Very unclear'

He said: "A larger percentage of white residents than black or Asian residents supported the scheme."

He said the time saved in completing arrest formalities and preparing court papers could be put into crime-fighting use.

Deputy Assistant Commissioner Mike Fuller, who has been overseeing the project, said: "The public were very unclear about what was happening and thought drugs were being legalised and that wasn't the case.

"Officers are still seizing the cannabis. Communication is going to be a key issue in any new scheme which arises from the pilot."

The Lambeth Cannabis Warning Scheme has been subjected to two evaluations in the six months since it began in July last year.

Criminal activity

As well as the Mori survey, which looks at local and national attitudes to the scheme, statistical analysis of the scheme's impact and police officers' feedback has been carried out.

Mr Fuller has been asked to analyse the findings from the two surveys and consider the potential impact for the rest of the capital.

A working group will now undertake further analysis of the pilot focusing on a number of areas, including how the saving of police time can be used effectively.

Mr Fuller said: "I will be looking at how the police time saved as a consequence of this scheme was used to tackle wider criminal activity in the borough of Lambeth."

Wider consultation with the Home Office and the Metropolitan Police Authority will take place before a decision on the future of the scheme is made.