That was Skeptics Society chair Vicki Hyde's response to billboards claiming the world will end on May 21.

An American evangelical group, known as Family Radio, has paid for billboards to be put up across New Zealand including Christchurch and Auckland, telling people to "Blow the trumpet...warn the people" as judgment day is coming.

"Hopefully people will look at it and think it's yet another movie ad...I've lost count of the number of judgment days I've lived through," Ms Hyde told NZPA.

The group was preying on vulnerable New Zealanders already on edge following Christchurch's deadly quake on February 22, she said.

"I've think we've had enough of doomsday scenarios, frankly, I mean, we've lived through Ken Ring's one."

Ms Hyde was referring to the weather forecaster's prediction of a big quake on March 20 in Christchurch, which prompted hundreds of residents to leave the city for the weekend.

There was a fine line between freedom of speech and creating unnecessary fear: "You can see the kind of serious harm that publicly promoted idle comments can do."

However, the society advocated critical thought and dissent and she did not call for the billboards to come down.

"Personally, I'd say let it be because we live in a nation of free speech where people are assumed to be adult enough to make up their own minds, but we're also concerned about the fact that these kind of things do prey on the minds of the vulnerable.

"And at the moment I think more of the population is feeling vulnerable to this kind of stuff than usual."

She was not surprised an international group was advertising its message in New Zealand.

"We are seeing the spread of evangelical fundamentalist Christianity for political and cultural reasons," she said.

Such billboards were a branding exercise for evangelical groups to gain attention, promote their ideas and recruit followers, she said.

Ms Hyde suggested Tui, known for its cheeky advertising, put out a billboard saying "The end of the world is coming. Yeah, right".

Wellington Presbyterian minister Rev Stuart Simpson, of Wellington's St John's in the City, said he did not endorse the message.

"With all the stuff that is going on right now, especially in New Zealand...people are just so on edge.

"To have stuff like this just causes more fear, I don't think it helps anybody," he told NZPA.

St John's was busy supporting people who were struggling to cope after Christchurch's devastating earthquake and fear-mongering made the situation worse.

He said the church believed a judgement day was coming but the scripture did not reveal a date.

"You just see throughout history the number of these groups that come up and say something (about judgement day) and then the time disappears and they are left with their foot in their mouth really," he said.

Wellington City Council spokesman Richard MacLean told NZPA he was unaware of any of the billboards in Wellington.

However, he said the council did have the power to remove offensive billboards - it had made a Karori resident remove a giant swastika from the side of his house, for example.

If it was a grossly offensive billboard that caused widespread offence then the police could get involved, he said.

Advertising company OGGI, owner of the billboard sites, could not be reached for comment.