Labour seems to have an "addiction" to gambling, shadow culture secretary Hugo Swire has said after sites for 17 casinos were announced.
Manchester was congratulated for its casino licence by Hugo Swire
Manchester was the surprise preferred choice for the first "super-casino", with eight more large casinos and eight small throughout Britain.
While congratulating Manchester, he said a pilot was needed to assess the impact on crime and the community.
Culture Secretary Tessa Jowell said problem gambling would be tackled.
She also said the UK's gambling regime would be one of the "toughest" in the world, apart from those places which ban gambling outright.
Mr Swire described Tuesday's announcement as the latest chapter of "this government's seeming addiction to gambling, no doubt lured by the prospect of tax revenues on the scale we now see in Australia."
He expressed concerns that the number of casinos would be increased "by the back door". He called for a debate and vote in both Houses of Parliament if an increase was proposed.
"I can say categorically today that we support a pilot scheme of one regional casino. There should be no change until there has been a proper assessment," he said.
Mr Swire was also concerned that preferred bidders were already lined up, but Ms Jowell reiterated that there would be an open competition for the licences.
He said there had been "an unprecedented change" in the last decade in way people can access gambling - through the internet, in pubs and at casinos.
"The government will rightly be judged on the consequences of this on society."
The licence will allow Manchester to build a venue for up to 1,250 unlimited-jackpot gaming machines.
Manchester's bid organisers said it would regenerate a poor area in the east of the city, promising a £265m investment and 2,700 direct and indirect jobs.
The casino would be based at Sportcity in the Beswick area, close to the City of Manchester Stadium.