At 7am tomorrow approximately 3000 junior doctors will walk off the job nationwide until Friday morning, with their union and the district health boards still locked in a war of words and no end to the dispute in sight.

It is their second strike action since October, a prospect that's left DHBs feeling frustrated.

"We are really talking about thousands of people across New Zealand who now have their surgery or outpatient appointments postponed because of this, I think, quite outrageous industrial action," says lead DHB CEO negotiator Julie Patterson.

Junior doctors say they are striking with a heavy heart.

"I can only apologise to patients," says Christchurch oncology registrar Dr Jonathan Davis.

"We don't want to be here but this is what we need to do to make sure things are safer for them in the long run."

For the past 12 months the junior doctors' union, the Resident Doctors' Association (RDA), has been fighting to reduce members' 12-day-in-a-row shifts and seven-in-a-row night shifts, arguing junior doctors are so exhausted that they risk falling sleep on the job, risking patient safety.

But DHBs claim they have already met union demands and agreed to reduce these shifts, and have also offered junior doctors a pay rise as well.

They now accuse the RDA of 'moving the goalposts' to make extra demands.

"The DHBs have met all those health and safety claims. Now the issues have shifted and they've shifted to a space the DHB’s just cant manage," says Ms Patterson.

She says the union is now demanding inflexible rostering arrangements for it’s members, which DHBs can never make work.

We're on strike this week because the CEOs want us to be on strike this week - Christchurch oncology registrar Dr Jonathan Davis

'We've had no offer'

The RDA says this week's strike could potentially have been avoided, if only the DHBs' CEOs had attended bargaining meetings last week.

"We reached what we thought was a reasonable agreement at the table," says RDA Secretary Deborah Powell.

"The problem now is that the DHBs wont get to consider that now until we meet on Thursday.

"We've had no offer, we don't know what they're going to say. That's why the strike has to go ahead."

Dr Davis says: We're on strike this week because the CEOs want us to be on strike this week."

But Ms Patterson says there was a good chance last week's bargaining was unlikely to have been accepted by DHBs anyway.

She also says with 20 DHB CEOs to consider, it is normal practice for professional advocates to attend some bargaining meetings on a CEO's behalf, as happened last week, and then report back.

"Deborah Powell, the union Secretary, is very aware of these processes so it's nothing short of mischievous to claim it's because the DHBs weren't at the table," she says.

The public are being encouraged to visit their GP or after-hours clinic from tomorrow morning until Friday morning unless it is a case of genuine emergency health need.