The Health Minister says he'll take action if he sees District Health Boards not doing their job.

It comes as recent financial results show the total DHB deficit has jumped $40 million in the last month.

It's the single largest deficit increase since the last days of the National government in September 2017.

The 20 DHBs have a deficit of $264 million overall, with only South Canterbury in the black.

David Clark told Mike Hosking he does worry about the situation.

"I've recently put a crown monitor into Counties Manukau, and I am prepared to act further if I see other DHB's that aren't performing."

He says that industrial action has played a part in the deficit increase.

Nurses, doctors and hospital staff are among those who've taken industrial action, with it being revealed this week that the junior doctors' strikes cost DHB's $19 million.

Clark say some of the costs relate to outsourcing in response to the interruptions.

"Fortunately, the majority of those industrial disputes have not been settled, so that does make things a little more straightforward."