Prime Minister John Key says American whistleblower Edward Snowden is not welcome here.

His comments follow media reports in which Australian barrister Geoffrey Robertson said Snowden would likely have a more "pleasant" refuge in New Zealand than North Korea or Russia.

Snowden was believed to be in Hong Kong after leaking information about United States intelligence agencies' monitoring of internet traffic.

Key said today the former security contractor did not meet the requirements for asylum and it was ridiculous to suggest he would.

"He wouldn't be welcome," he said.

Key couldn't rule out Snowden coming to New Zealand under another immigration category because he was not facing criminal charges.

But the prime minister expected the Government would oppose any asylum application.

"I can't see why we'd want him to turn up," he said.

"He's welcome to apply to come here but not as an asylum-seeker, that was the [premise] of the article."

New Zealand was a good fair country which upheld its responsibilities under international law and that was the case with the extradition of internet millionaire Kim Dotcom, he said.

"We don't have a view on his [Dotcom's] particular case - as we've said so often before, it's really a matter between the United States and Mr Dotcom," he said.

"They're invoking the extradition treaty and we're playing our part as a treaty partner."

Green Party co-leader Russel Norman said he couldn't understand why anyone would not want Snowden here.

"He was a whistleblower inside the organisation, he made a moral decision I think most people on planet Earth would agree with the morality of his decision," Norman said.

Key has also been asked about the presence of US spy software company Palantir which has established a base in Wellington.

He said he knew who they were but didn't speak for the company.