Controversial ads promoting atheism will soon appear on billboards throughout New Zealand after a transport company backtracked on allowing them on its buses.



The ads - which read "There's probably no God. Now stop worrying and enjoy your life" - created a storm when they ran on buses in the United Kingdom last year.



The Atheist Bus Campaign last year raised more than $22,000 to fund the ads, but NZ Bus declined to run them after receiving a number of complaints from the public and staff.



The group applied for legal representation from the Office of Human Rights Proceedings in March to pursue a discrimination case against the company.



Campaign spokesman Simon Fisher said the billboards would get the atheist message out into the public while the group awaited the office's decision.



"It's been really good to get things moving again, and I'm sure everyone's keen to see some advertising out there," he said.



About $10,000 - roughly half the campaign's funds - would go towards the billboards.



"We're still keen to go ahead with the discrimination case against NZ Bus, and therefore we still need to be able to follow through with the bus campaign at the end of the day. So we need money aside for a bus campaign if we do win," Mr Fisher said.



The ads should appear on billboards in Auckland, Wellington and Christchurch within two to three weeks, he said.



"The sites that we've been looking at are great - the central locations."



The campaign would move from the cities to smaller centres after a few months, Mr Fisher said.



"The beauty of billboards is that you can move them around easily. It's a relatively small cost to change the site of the billboards."



He did not anticipate site owners would object to the ads.



"It's just a matter of getting the individual site owners' permission, but generally I think that's fine," he said.



An online "billboard generator" has been set up on the campaign's website to gather new ideas for campaign slogans.



"It's been really good, we got about 300 that are actually usable - they don't slander other people or they're not completely silly," Mr Fisher said.



"We'll pick three or four, and then we'll use those."



NZ Bus earlier this year said it declined to run the ads because the campaign had drawn a "significant reaction" from passengers and staff, with a number finding it distasteful or distressing.



"NZ Bus has the right to decline advertising that may, in its perception, be considered controversial or divisive," spokeswoman Siobhan O'Donovan said.