"It's not so much that we were happy to have them here at the time, but certainly if we look at what's happening now around the world and the action Russia has taken New Zealand needs to work out its foreign policy position on this."
Peters yesterday confirmed there was Russian intelligence activity in New Zealand.
In answer to a question in Parliament, Peters said: "The NZ SIS advise us it is aware of Russian intelligence activity in New Zealand and where it is seen, appropriate action is taken.
"I am advised by the NZSIS, and so has the Prime Minister been, that there is no individual here in New Zealand that fits the profile of those being expelled by other countries and that is people within the embassies in other countries. If there were, we would have taken action a long time before Salisbury."
Peters said New Zealand's Five Eyes security partners were consulted.
"People in the Five Eyes have consulted with us on our decision, understand our decision and did so before the decision was made."
Five Eyes is the intelligence-sharing alliance between New Zealand, Australia, Canada, the UK and the US.
Speaking later, Peters said when people were perceived to be spying in New Zealand, if the SIS and other security agencies needed to take action they would.
"The NZ SIS told us that within the description that we're seeing being expelled offshore, there were none in the Russian Embassy in New Zealand that fitted that and we took that advice. That doesn't mean that with respect to other surveillance that's illegal, in terms of intelligence and espionage that the SIS and agencies are not acting. Bear in mind, most of this surveillance or intelligence activity is taking place offshore but nevertheless could be against New Zealand."
Earlier, Ardern said New Zealand was looking into stopping New Zealand visas being issued to some people of Russian origin.
Ardern said she had asked Foreign Affairs and Trade officials about further measures New Zealand could take against Russia.
"For instance, around the issuing of visas for particular people of Russian origin who may be in some way inappropriate for travel to New Zealand. I'm awaiting that advice."
She said the fact there were no Russian spies did not mean New Zealand was not the subject of intelligence gathering by, for instance, attaches.
"People acting as spies do not declare themselves as such."
She rejected criticism from the Opposition that she had mishandled the issue.
"I would expect that the Opposition would do the same thing I have, that is, listen to the advice from the NZ SIS on whether or not we have any undeclared intelligence officers here.
"The advice was we didn't. That advice was verified by our partners. I had to act on that advice.
"New Zealand has done exactly the same thing as our partners, including Australia."