The union representing public servants said scientists should be able to voice their concerns without copping criticism from government ministers.

The Acting Civil Defence Minister has blasted the director of Geonet Dr Ken Gledhill for going public with comments about Geonet funding and resourcing.

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Gerry Brownlee said he's been blindsided by what he says are "unreasonable" comments, that better technology and increased funding would help the Geonet service.

Public Service Association National Secretary Erin Polaczuk said their members too often feel afraid to give the frank and fearless advice they're employed to deliver.

"It's really sad actually for our democracy if members of the public service feel intimidated by their Ministers."

Polaczuk said scientists who work for the Government should be able to voice concerns when they have them, and Mr Brownlee shouldn't have lashed out.

"I think it was really unfair of him to use his position in that way, when all that was happening was a scientist raising concerns, that had already been raised with the Minister in the past."