Tab.co.nz, the website of the New Zealand Racing Board, came under attack from cyber hackers over the Christmas period, the Dominion Post reports.

Tab.com.nz

Customers across the country were unable to place bets online after the betting website crashed. TAB general manager Glenn Patrick said the site had come under “unprecedented and concentrated” cyber attack from unknown sources.

"We've probably had seven or eight occurrences," he said. "We have firewalls which are doing their job effectively."