The search for people who may have been trapped in an Auckland stormwater drain has been called off.

Divers have completed a search of the 1.5 kilometre-long drain in Mt Albert and found nobody trapped inside.

Two police divers descended into the stormwater drain this afternoon to search after workmen earlier heard what they thought were cries for help.

Emergency services, including four fire crews, attended.

The fire service was first called to the scene at Alberton Ave, Mt Albert, outside Mt Albert Grammar School, about 1.30pm but has yet to find any trace of anybody.

"The workmen thought they heard voices, muffled voices of people crying for help," Fire Service northern communications shift manager Steve Smith told NZPA.

"They assumed because it was next to the school that it was children."

Mr Smith said three crews were near the culvert at the school and one was where the culvert meets the ocean at Point Chevalier looking for signs of anyone.

"We are liaising with the Auckland Regional Council and we're waiting for the water level to drop."

Mr Smith said the Fire Service asked Mt Albert Grammar and nearby Marist School to do roll calls and no students appeared to be missing.

- NZPA, additional reporting by nzherald staff and Newstalk ZB