Police have suspended all flights at Auckland Airport as they respond to a threat near the domestic terminal.

Officers are responding to reports of "a threat'' near the airport and have been at a spot on Geoffrey Roberts Rd, near the airport, since about 8am local time (6am AEDT), the New Zealand Herald reports.

Auckland Airport said all flights had been suspended by police until 9.15am local time (7.15am AEDT).

Police have now cleared the runway to open and all flights have resumed.

A police statement said specialist groups were on site and are conducting inquiries.

Parts of roads surrounding the airport are closed as police work at the scene.

Motorists are also being warned to expect delays.

"Police appreciate motorists co-operation ahead of time as we conduct those inquiries at the location," police said.

An Auckland Airport spokeswoman said operations were not affected by the threat and staff were assisting police.

"Police are in charge of the situation. The area where operations were focused was in the airport precinct and away from both the international and domestic terminals, she said.

Mayank Batra, an operations controller at Swissport Executive Aviation across the road, said the Air New Zealand Airport Campus was being evacuated.

Members of the public heading to the domestic terminal are being told to use an alternative road instead.

"Significant delays are expected,'' police said.

His colleagues were not being allowed down Geoffrey Roberts Rd. Police were telling them there was a bomb threat in the campus carpark.

Mr Batra could see six to seven police cars and a fire truck. His building was also being evacuated.

This article originally appeared on the New Zealand Herald and was reproduced with permission