Professor Colin Drummond is a government advisor on alcohol
The government has been accused of "sexing down" a draft report on alcohol misuse to prevent the study damaging the case for extending pub opening hours.
The new Licencing Act paves the way for local authorities to extend pub hours and even allow 24-hour drinking from next year.
The national Alcohol Harm Reduction Strategy published in March did not include evidence from Australia and other countries about the damaging effects of longer opening times. Yet that same evidence had been included in a draft interim report obtained by Panorama.
Professor Colin Drummond was not involved in the leak but told the BBC's Panorama: "I think it's an example of sexing down a dossier on alcohol problems, that evidence that was clearly available was not included in their final report."
The professor of addiction psychiatry at St George's Hospital Medical School served as an advisor for the strategy report.
Under the government's Licensing Act 2003, which was published in March, local authorities and not magistrates will grant licences.
The proposals, originally promised before the last election, could mean 24 hour drinking in some pubs, which the government claims will help cut crime by reducing binge drinking.
Binge drinking can lead to problems in city centres after closing time
But Professor Drummond, a government advisor on alcohol, is not so sure.
He added: "The mainstay of that act is to extend licensing hours with the hope that will reduce the alcohol related disorder around pub closing times and spread it through the whole evening."
"But there is research around which suggests that having 24-hour licensing will actually increase rather than decrease problems. It may change the nature of the problem as well."
"There are various studies from, for example from Western Australia, showing that extending the licensing hours can actually increase the amount people are drinking and the amount of problems associated with drinking."
Professor Drummond also claimed that much detailed research about ways to control the alcohol problem by raising prices and making it less affordable was also not included in the final report.
He added: "One of the striking things was that when the final report was published there were a great number of things that really just didn't appear there at all.
"One was about the affordability of alcohol and the fact that if you reduced the affordability of alcohol you also reduce alcohol consumption and the harm associated with it."
"I think it's extremely important and certainly the academics and the Royal Colleges that commented on the strategy are very concerned that these things had been left out."
But the government points to evidence that flexible licensing hours will reduce binge drinking and associated crime.
Richard Caborn MP says the law aims to regenerate local economies
The Minister for Sport and Tourism, Richard Caborn MP, has day-to-day responsibility for licensing.
He says the government's case is supported by the results of pilot schemes mounted at New Year and the Nicholson Committee review of liquor licensing law in Scotland.
"All the bodies that we've consulted collectively - local government associations, the police, the industry have all said that they wanted relaxation of licensing. They did not believe it was going to create a problem."
Richard Caborn says the law is part of a wider reform of local government: "Our end objective is to regenerate the economies and to give local authorities more power"
He says: "What I want to see is the drinks industry getting in with local authorities to develop the local economies."
"We want to create some of our cities to be leading European cities of the future. As tourism minister I'm out there saying: "Come and visit this great country of ours, oh by the way you can't have a drink after 11 O'clock. That's crazy."
Panorama: Cldnt Give a XXXX 4 Lst Ordrs was broadcast on BBC One on Sunday, 6 June 2004 at 22:15 BST