Big name brands including casino sites from Betfred, Littlewoods and William Hill, as well as popular site Interpoker.com will fall foul of the ban, due to where they hold their gambling licenses.
While companies operating in gambling jurisdictions within the European Economic Area (EEA) are permitted to advertise, territories outside the zone had to apply to be included on the government's white list by proving their security and responsibility.
Alderney and the Isle of Man have made the grade. Media agencies that could face new business opportunities are waiting for a ruling on Antigua while Costa Rica was the biggest gambling centre that did not apply.
Under the legislation sites will be banned from advertising across the board including on TV and radio, in newspapers, magazines and online.
Gambling firms within the EEA can look forward to relaxed laws around advertising when the Gambling Act 2005 is introduced next month. But the latest legislation is a twist that will exclude some major players.