Tessa Jowell exaggerated the case for supercasinos, according to the head of the watchdog which will oversee gambling reforms.
In an interview with the Times the chairman of the new Gambling Commission, Peter Dean, contradicted the culture secretary's claim that supercasinos will not create more gambling addicts.
The Gambling Act, passed in May, will from 2009 introduce supercasinos with up to 1,250 million-pound slot machines.
Dean said that he does not think it is realistic to expect the Gambling Commission to reverse the trend of problem gambling despite that being the aim of the organisation.
"We should not regulate onerously for the sake of being butch. I think that's absolutely unnecessary and inappropriate," he said.
Dean went on to criticise the government's "exaggeration" of its case for gambling reform.
"There should not be proportionately more problem gamblers following an increased access to gambling," he said.
"Although it's a very desirable objective to reduce the number of problem gamblers, which we will do, as a realistic expectation what one should be aiming to do is certainly not exceed a proportionate increase."
His comments contradict Jowell, who told a parliamentary committee: "If problem gambling rises then [the Bill] would have failed and it would be bad legislation and it would have defeated the intention and the purposes that we have."
A spokesman for the Department for Culture, Media and Sport said: "The Gambling Commission exists to implement the Gambling Act and we make no apologies for the tough new protection the Act introduces."
