The Labour Party has posted an ad on Facebook featuring a visit by Prime Minister Jacinda Ardern to ESR and the national contact tracing centre, with a brief appearance by director general of health Ashley Bloomfield.
Act leader David Seymour described it is scandalous and that no public servants should be used to help political parties to campaign.
But a spokeswoman for Ardern said the advert did not break any rules, despite the decision later being taken to take the advert down for a re-edit.
"To even think it might be okay to go and use a Government department to shoot a political ad is just extraordinary," Seymour said.
"One of the hallmarks of a democracy is you don't get to use the power of Government for your own re-election."
When first contacted by the Herald on Saturday afteroon, a spokeswoman for Ardern denied it was a Labour campaign ad.
"The video is an update on the Government's covid response and specifically the work ESR and the national contract tracing team has been doing," she said.
"The Prime Minister's update are shared on the Labour Party channels as it permitted within the rules," she said.
Then on Saturday night, while saying "we maintain our position that the video is within the rules", the spokeswoman said the advert was being taken down "to re-edit so as to remove any concern over public servants being shown".
Seymour said the ad presented "a massive conflict between her interests as Labour leader and her interests as Prime Minister."
Seymour also believed it would make it harder for Ardern to do her job in holding the public service to account.
"This is the guy, Ashley Bloomfield, who is in my view responsible for quite a number of failings.
"If he is helping her get re-elected in her capacity as Labour leader, can we be sure that she will hold him accountable in her capacity as the Prime Minister?"
Ardern made the visits on Thursday.
News media were restricted in the number of cameras and reporters at ESR in Porirua where genome sequencing work is being done on Covid-19 cases.
Reporters were not told about Ardern's visit to the national contact tracing centre.
Bloomfield has been at the centre of the latest Covid-19 testing controversy over how often at-risk staff were being tested. The Government thought it was weekly, but weekly tests have now only just begun since community transmission was detected in Auckland on August 11.
He has shared a stage with Ardern many times during the Covid-19 crisis and frequently since August 11.