Six Londoners die each week as a result of drug misuse, Ken Livingstone has warned.

Hosting the first alcohol and drug summit, the mayor has said that drug misuse is significantly higher in London than the rest of the UK.

The summit comes as a new report by the Greater London Alcohol and Drug Alliance and the London Health Observatory warns that the capital's 70,000 problem drug users cost the city £2.5 billion a year.

Livingstone said it was important to ensure "a more co-ordinated approach" is taken to reduce the effects of drug and alcohol use in London.

"These are developing a strategy against crack cocaine, addressing the link between homelessness and drug and alcohol problems, tackling social exclusion in London through action on alcohol and drug misuse, and promoting the role of the community in preventing drug and drug and alcohol problems," he said.

Bob Ainsworth, the Home Office minister with responsibility for the government's anti-drugs strategy, said London "has a substantial drug problem".

"Most drug-related crime in London is committed by the estimated 70,000 chaotic drug users in the city, so getting drug-using offenders into treatment is a key priority of the government's drug strategy," he said.

Metropolitan Police chief Sir John Stevens said drugs were doing "great harm" to the capital.

"The Met has a twin-track strategy to combat drugs in London, pairing enforcement activity to prosecute dealers with our ongoing efforts to divert people from drugs and educate on the dangers they present," said Sir John.

"There is no single solution that can be provided by any one organisation, we must work together to find the answers."

The report reveals that Londoners are more likely than people in other parts of the country to have used illicit drugs.

Thirty-one per cent of 16 to 29-year-olds in London claim to have taken an illegal drug in the past year, compared to a national average of 25 per cent.

Six per cent of Londoners had used class A drugs in the last month, the study claimed.