The online poker industry is thought to be worth about $5.1bn (€3.5bn), or 17pc of the gambling industry on the web.
The sector has been fighting an ongoing battle with authorities in the US, however, which has some of the strictest gambling laws in the world.
Earlier this month, the US moved against three poker websites: Full Tilt; Isle of Man-based PokerStars; and Costa Rica's Absolute Poker. The US alleged that the companies used fraudulent means to circumvent federal laws and "trick" banks into processing payments on their behalf. The government is seeking at least $3bn in forfeitures and penalties.
Warrants have been issued for 11 people involved in the three companies, including Full Tilt's founder Raymond Bitar.