Global gambling heavyweight The Stars Group has dramatically upped its bet on the Australian sports-betting market, raising its stake in digital bookmaker CrownBet to 80 per cent.

The Canadian-based company behind some of the world's biggest and best-known online poker sites made its foray into Australia last month when it spent $150 million buying a 62 per cent stake in CrownBet from James Packer's casino group, Crown Resorts.

Now it has lifted its ownership to 80 per cent announcing the move to the Toronto stock exchange after CrownBet emerged as the winning bidder for the Australian assets of a major competitor, William Hill.

In a statement, The Stars Group, which runs the popular PokerStars online poker site and has 115 million customers worldwide, said the aggregate price of its CrownBet ownership increase and the William Hill transaction was about $400 million.

"These acquisitions will further increase our exposure to the attractive regulated Australian sportsbook market and create a player of scale and clear rival to the top two operators there," The Stars Group chief executive Rafi Ashkenazi said.