National is seeking to have "Sign-gate" added to a range of other "gate" scandals it has pinned on Prime Minister Helen Clark.
The Wellington Airport Company has angered National by not accepting a party billboard attacking Helen Clark that it wished to display on one of the airport'sadvertising sites.
Senior National MP Bill English yesterday said fear of a Government backlash was behind the airport turning down the sign.
"Wellington Airport, like everyone else, saw Helen Clark's assault on the Auditor-General and Labour's plans to legislate to stop people who don't belong to political parties criticising the Government next election." Mr English said.
"These actions have created a climate of fear."
The airport had previously carried billboards for political parties, an airport company spokeswoman said.
"We declined the proposal to put this particular ad at the entrance to the airport.
"We do decline ads at the airport from time to time. That's basically all we're saying about it."
The billboard went up in Auckland and Christchurch yesterday.
The Christchurch billboard is on the side of a building housing an electorate office used by Labour MP Clayton Cosgrove.
Labour Cabinet Minister Steve Maharey said:"Labour doesn't intend to be distracted by this, but we will not accept this kind of ongoing character assassination that serves very narrow interests."
