About 1,000 gambling websites based overseas are to be banned from advertising in the UK.
Online gambling is becoming more popular, surveys suggest
Littlewoodscasino.com, Betfred Casino and Interpoker.com are among those subject to the ban, which comes into force next month.
Culture Secretary James Purnell said protecting the public from sites operating without the UK's "strict standards" was a "priority".
Broadcasters and publishers breaching the rules could face fines or prison.
The Department for Culture, Media and Sport (DCMS) said the aim was to stop unregulated gambling sites trying to attract UK punters.
Sites in the UK, Europe and other "white list" areas can advertise on TV, radio and in print media, subject to UK advertising rules.
To make it on to this list, companies must show they are subject to a suitably stringent regulatory regime.
This includes measures on stopping children gambling, protecting vulnerable people, ensuring games are fair and keeping out organised crime
Mr Purnell said: "I make no apology for banning adverts for websites operating from places that don't meet our strict standards. Protection is my number one priority."
The new rules take effect on 1 September , when the Gambling Act comes fully into force.
The legislation also brings a relaxation of the current rules surrounding adverts for all types of gambling companies, including casinos and betting shops.
Gambling sites operating from the EU, Iceland, Liechtenstein, Norway, Gibraltar, the Isle of Man, Alderney and other white-listed countries will still be allowed to advertise in the UK.
Littlewoodscasino.com, Interpoker.com, Betfred Casino and Poker are among the sites subject to the new advertising ban because they are all currently based in Caribbean islands the Netherlands Antilles, the DCMS said.
The Gambling Commission has compiled figures that suggest the number of people going online to place a bet in the UK is increasing.
Surveys carried out in the year to June 2007 indicated that 8.6% of adults had taken part in at least one form of "remote gambling" during the previous month, up from the 7.4% seen in 2006 polls.