The ban will be implemented across London's entire transport network
Plans to ban the drinking of alcohol on London's transport system have been unveiled by new mayor Boris Johnson.
He joined London's transport commissioner Peter Hendy to set out a timeline for bringing in the measure.
The ban, starting on 1 June, on the Tube, buses, trams and Docklands Light Railway is one of his election pledges.
But the Rail Maritime and Transport Union said the policy appeared "not to have been thought through very well" and could make matters worse.
It is part of Mr Johnson's wider strategy to tackle anti-social behaviour. New posters were also unveiled advising passengers of the no-alcohol policy.
The mayor said: "I firmly believe that if we drive out so-called minor crime then we will be able to get a firm grip on more serious crime.
"That's why from 1 June the drinking of alcohol will be banned from the Tube, tram, bus, and Docklands Light Railway."
The ban on the London Overground will take longer, as Transport for London has to apply to the Department for Transport for permission to enforce the bar on the consumption of alcohol.
Don Shenker, chief executive of Alcohol Concern, said: "Public drinking and the behaviour sometimes associated with it can, and does, deeply affect people's ability to enjoy public spaces.
"Taking a firm approach to public drinking in this way sends a strong message that public drunkenness is socially unacceptable."
But the Rail Maritime and Transport (RMT) Union's leader Bob Crow said: "We are in favour of any measure that will make our members' lives safer and curb anti-social behaviour, but it appears that this really hasn't been thought through very well and could well make matters worse.
"We are being told that it will be our members who will have to approach people drinking and ask them to stop - but the mayor hasn't asked us what we think.
"Perhaps the mayor will come out with his underpants on over his trousers like Superman one Saturday to show us how it should be done, and maybe tell a crowd of Liverpool supporters that they can't drink on the train."