The TAB says it has been hit by a cyber attack that has crashed its website several times over the past two days.
But it says its customers' financial information is still secure.
TAB general manager Glenn Patrick said the board had received some information about who was behind the attack, which it will provide to the police. The betting agency is fighting back with blocking techniques.
Patrick said the board was apologising to customers who had been unable to place bets on the website, but he said the TAB would not lose much of its turnover.