By Sarah McDougall of NZPA

A blaze at chicken hatchery in a rural area south of Auckland destroyed 200,000 fertilised eggs.

About 68 firefighters and 15 appliances battled the blaze tonight at the hatchery on Brown Rd in Tuakau, northern fire communications shift manager Steve Smith said.

A staff member discovered smoke coming from the roof of the hatchery about 3pm.

Bromley Park Hatcheries chief executive Stuart Weston told NZPA the hatchery, which was about 20 by 30 metres, stored about 200,000 eggs which were all destroyed along with the building.

There were no live chickens at the site, as most fertilised eggs were kept cool and any chicks which had hatched after a 21 day warming cycle were promptly removed, he said. Breeding chickens were kept at other farms.

The number of eggs destroyed was a small proportion for the business, which produced tens of millions of eggs a year, Mr Weston said.

The fire had not spread to any of the surrounding buildings, including the business headquarters and staff homes.

It was not clear what caused the fire, but there had been no indications it was suspicious, he said.

Mr Weston said he was impressed by the voluntary fire service, who were quick to the scene.

"They were very, very well organised and everybody knew what they were doing. It was a very impressive display. So we were very grateful to the fire service for what they did."

The fire service would be investigating the cause on Monday.

The company had insurance and the hatchery would be rebuilt, Mr Weston said.

He was not sure how long that would take, but said specialist incubation equipment would need to be shipped in from overseas.

In the meantime, the approximately 30 staff who worked at the site would likely be transported to work at one of the company's other hatcheries, he said.

The company employed about 150 people in total and had several sites in operation, he said.

"Other than the trauma of seeing something we've put a lot of effort into going up in smoke, in fact the impact to the business is negligible."