Key Points:

The National Party has accused Wellington Airport of refusing to display a billboard criticising the Government because it is too politically sensitive.

The billboard features a picture of Prime Minister Helen Clark with the words: paintergate, corngate, doonegate, speedgate, pledgegate and then, above her head, departure gate.

National MP Bill English today said the party had erected billboards attacking the Government at sites in Christchurch and Auckland, but Wellington Airport had refused to take one.

He said last year the airport had accepted billboards critical of the Government and questioned whether the change of heart was due to attacks by government ministers on the Auditor-General over his recent report on unlawful election spending.

"These actions have created a climate of fear and more so for a company doing business with government-owned Air New Zealand."

Mr English said the airport company had already annoyed the Government by opposing Air New Zealand's proposed trans-Tasman codeshare with Qantas.

A spokeswoman for Wellington Airport declined to comment on the reasons behind the decision, but said billboards were declined "from time to time".

Mr English said the billboards were paid for out of party funds.