The Gibraltar Betting and Gaming Association has said it will resist changes laid out the draft UK Gambling Act and has set aside £500,000 to pursue legal action if necessary.
The point-of-consumption tax proposals would have a significant effect on Gibraltar-based operators, with the GBGA claiming the tax would unfairly favour British companies.
Figures provided by the GBGA show that the Gibraltar-licensed companies, which include William Hill and bwin.party, account for 12 per cent of all jobs in the territory and 15 per cent of tax revenue.
The tax would come into effect in December 2014.
