The cyber attack on the Waikato District Health Board should have been anticipated.

The attack's crashed phone lines and computers - blocking all IT services except email in Waikato, Thames, Tokoroa, Te Kūiti and Taumarunui hospitals.

Elective surgeries have been postponed and patient notes can't be accessed.

IT security expert Daniel Ayers told Mike Hosking they were sitting ducks and there's no excuse for it.

"You have to ask yourself, what sort of incentive do we need to encourage managers and organisations, and the government, to prevent this from happening."

"This is serious business when this impacts a hospital."

He says cyber criminals are targeting the health sector at the moment.

"There has been a number of health organisations attacked in the last month [or so], but I think they will be attempting this against a lot of health organisations and succeeding against relatively few."

The problem is not expected to be resolved until the weekend at the earliest.

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