Laboratory workers will strike in labs currently testing for the novel coronavirus - a protest that comes at a "poor time", according to Director-General of Health Dr Ashley Bloomfield.

District Health Board (DHB) medical laboratory workers and NZ Blood Service employees, who are members of the APEX union, will strike on March 13.

"[This is] in support of achieving a fair offer to settle their multi-employer collective agreement," an APEX press release said on Monday.

The union says the strike action will cover two of the three laboratories currently testing for COVID-19. These are two DHB labs - LabPLUS in Auckland and Canterbury Health Laboratories in Christchurch. The third is ESR, which is not covered by APEX.

The strike will accompany ongoing partial strike action that will run until May.

The processing of COVID-19 samples will continue - but in the face of "considerable disruption" to the labs where the testing takes place.

"The employers have made no effort to reach a fair agreement," senior APEX advocate David Munro says. "The employers' most recent offer discriminates against our members and would lock them into inferior salaries for the term of the collective agreement and beyond."

Despite APEX's laboratory scientist members holding university qualifications, they earn 12 percent less than a similarly qualified, registered nurse. They also earn more than 7 percent less than identically-qualified colleagues working alongside them, but on a different employment agreement, according to the press release.

Munro claims that employers are unprepared to settle the dispute and eliminate the disruption to the labs.

"It couldn't be a worse time.  Now is when we should all be pulling together to fight coronavirus. Instead the employers prefer to fight their own staff."

Director-General of Health Dr Ashley Bloomfield said during a press conference on Monday that the timing "wasn't very good", but reiterated the strike will not impact testing for COVID-19.

"That strike will not affect our laboratory testing for COVID-19. Either the workers are not in laboratories, like ESR, there are no members in that lab. Or where they do have members in the Auckland lab, they are not involved in COVID-19 testing."

Dr Bloomfield said he's "disappointed" that the union are using the situation as "leverage".

"I'm disappointed they are using this situation to get leverage around an industrial matter that has been ongoing since last July... I don't think now is the time."

A "fairly robust discussion" was had with APEX national secretary Dr Deborah Powell.

"I told Dr Powell - and we've known each other for a number of years - that I just thought it was poor timing and that didn't mean we didn't want to resolve the industrial dispute, of course we do," Dr Bloomfield said during the COVID-19 update.

"But I thought it was poor timing to try and draw in the response to COVID-19 into that particular disagreement."

Munro says the solution is simple.

"The employers need to act on their own rhetoric and make an offer that ensures that colleagues doing identical work with identical qualifications and experience are paid the same.

"It is time that the Director-General of Health stepped in to settle this dispute at such a crucial time."

Dr Powell has also voiced her concerns that DHBs and the broader hospital system is overwhelmed and over-stretched. 

"Deborah's in the middle of a number of contract negotiations, so that's the context there," Dr Bloomfield said.

"Right from the start, we've talked about the need for our hospitals to have really good plans in primary care to ensure that we can cope with COVID-19 cases as they come through.

"Of course with our contact tracing and self-isolation... what we're trying to do is reduce the number of cases and that reduces the impact on our hospitals... I have talked with Deborah and she's agreed that what we really need is good ideas about how to address pressures on the hospital system."

What is a medical laboratory worker?

Medical laboratory workers are registered health professionals who run laboratories and test, interpret and report laboratory results. They are trained to identify disease and abnormalities through analysing blood, tissue and other bodily samples.