Prime Minister Tony Blair has defended plans to overhaul gambling laws, saying they need updating to protect children and those who already gamble.
Mr Blair denied the legislation would lead to more gambling
"The vast bulk of this legislation is actually about regulating gambling, not deregulating it," Mr Blair insisted.
He said he understood concerns but said there was "no evidence" changes would lead to gambling addiction and crime.
Tory leader Michael Howard said the government was on "the wrong track" and his party would oppose the Bill.
The Bill's proposals include the relaxation of rules on the construction of casinos and sweeping away player restrictions.
Mr Blair said people were already gambling, at betting shops, on the internet, on racing and football and casinos were only a small part of that.
"It's very important that we modernise the regulation of gambling for today's world," Mr Blair said at his monthly press conference.
"Whether we like it or not, we have gambling in this country, but with a series of rules and restrictions which are completely out of date."
"Ninety per cent of the gambling bill is about better regulation and protection for children, removing slot machines from about 6,000 premises where minors, children, might have access to them."
It was likely the shake-up would lead to between 20 and 40 new casinos - as compared to the existing 120, he said.
Casinos open 24 hours
Immediate access for public, no 24-hour joining period
Unlimited jackpots in largest casinos
Betting allowed on Good Friday and Christmas Day
A new criminal offence of inviting, permitting or causing a child to gamble
Compulsory age checks by gambling websites operating from the UK
Mystery shopper surveys by the Gambling Commission to check rules followed
Tighter restrictions on betting exchanges
Allowing casinos to advertise for first time
Asked who wanted more casinos, other than US operators, he said: "Go and talk to the people in Blackpool who urgently need the regeneration. For many of these places this is a chance to put it on a proper modern footing."
He also dismissed as "nonsense" claims that government officials had offered US gaming operators tax cuts to invest in British casinos.
The Times quoted a US article in which American Gaming Association head Frank Fahrenkopf allegedly said an offer to cut tax from 40% to 20% was made.
But Mr Fahrenkopf told Radio 4's Today programme: "I recommended that there be a reduction from present rates, but I got no commitment from anyone."
Culture Minister Lord McIntosh also described a newspaper story claiming ministers were "in retreat", dropping planned casino numbers from around 250 to 40 or less as "pure fantasy".
He told the BBC: "I said all the time we expected 20 or 30 or 40, the figure of 150 or 250 was built up out of nothing by the Daily Mail and followed by some others."
Labour MP Frank Field has now tabled a Commons motion calling on ministers to limit the law change to allow for trials for new "mega casinos".
A new ICM poll for the Guardian newspaper suggests 53% of voters do not believe Britain needs more casinos, with 34% backing plans to allow them and 12% undecided.