Proposed Las Vegas-style super casinos in London must bring life to run-down areas without increasing crime and problem gambling, a new report warns.
The London Assembly said the casinos must be far from housing and entertainment destinations on their own to avoid pitfalls.
Two large casinos, yet unseen in the UK, are likely to be built in the capital under the new Gambling Act.
London mayor Ken Livingstone favours the Dome in Greenwich, east London, and Wembley, northwest London, as sites for the development.
Major casino companies have also proposed the Olympia exhibition hall or the White City shopping center in Hammersmith, or West Ham Sands football club in Newham.
A tentative proposal for Stratford City, which overlaps with the Olympic Park, could affect the 2012 Games.
London's current 24 casinos represent less than a fifth of those countrywide. Yet last year almost £ 2.2 million was gambled in the capital - nearly 60 per cent of the national total.
Councils should have the final say over whether a casino is built in their area, the assembly said.
Casino companies should state how they would create jobs and use local suppliers in their planning applications, the report added.
"We cannot afford to be complacent," said Dee Doocey, chair of the assembly's economic development committee. "Super-casinos could change the social and economic fabric of the capital."