The chief executive of Austrian oil-exploration company OMV is to leave the company next year.
The company, which carries out offshore drilling in New Zealand, has been at the centre of reports it has spied on climate activists.
RNZ reported last week private investigators had spied on children who joined a peaceful protest against OMV in New Plymouth last year.
A two-year investigation by Nicky Hager found that they and other climate change groups were targets of the private investigation firm Thompson and Clark, paid by clients from the oil and gas industry.
OMV chief executive Rainer Seele has turned down a contract extension, announcing on Monday he would leave the company next year. OMV said the decision was based on personal reasons.
"It doesn't come as a surprise to us that Rainer Seele has now told the public that he is not going to prolong his contract," Greenpeace spokesperson in Austria Jasmin Duregger told Morning Report.
"So far we have only received little answers to our questions and this it's not clear to us what is really going on."
Duregger said OMV had confirmed to local media it has kept tabs on activists.
"They claim they do so as they need to actually monitor what the climate movement is doing, Duregger said.
"They claim to actually keep the climate protesters secure by doing so, which is absurd to us, because especially school strikers they are really peaceful.
"For us, that is not a good explanation."
Greenpeace has raised similar allegations in Austria with claims OMV used the investigation company Welund.
OMV is part-owned by the Austrian government and Vice-Chancellor Werner Kogler and Minister for Climate Action Leonore Gewessler, both of the Austrian Green Party, have demanded clarification on the spying allegations, the party's climate spokesperson Lukas Hammer said.
Gewessler said in a statement: "The current allegations are far-reaching and must be taken seriously. In this regard, I expect immediate and full clarification from OMV CEO Rainer Seele."
In a statement OMV said Seele's decision to leave the company when his current term of office expires, rather than taking up the one-year extension, was for personal reasons.
It said the company had no interest whatsoever in "spying" on NGOs or individuals.
"We have never given - nor would we ever give - instructions to target people no matter what age for surveillance," the statement said.
"We use public information that is freely available in order to avoid dangerous situations and to protect our facilities, our staff, and the activists themselves."
The company said OMV and all its partners work within all rules, regulations, and laws.
"Whenever protests have occurred, we liaised directly with Police and other regulatory bodies and took their advice on how to deal with the situation to ensure a peaceful outcome."