European countries have the power to ban inter-country online gambling, the EU Court of Justice has ruled.
But gaming bodies fearful of the implications of the ruling are fighting hard to overturn the precedent.
Dutch authorities had banned the nation's internet users from using the websites of UK-based gaming companies Ladbrokes and Betfair. The companies had appealed the block in the EU Court of Justice.
But the court has now found in the Dutch government's favor, the BBC said, and the ban stands.
The Dutch national lottery company, de Lotto, holds the exclusive license in the Netherlands for sports gambling. Critics of the block had argued that the move was an attempt to ensure de Lotto maintains a monopoly.
In their appeal, the UK gambling companies stated they held licenses issued by their homeland. But the court found that these licenses were irrelevant, as EU laws on online gambling have yet to be harmonized.
The region's online gambling industry is now campaigning for an overhaul of EU gambling laws, the Telegraph said.
Peak body EGBA has asked the EC to propose gambling legislation at an EU level, and to follow in the footsteps of Italy, Denmark and France by aiming to liberalise European gambling markets.