Several people have been taken to hospital and others have been treated by paramedics after a chemical leak at a chicken plant in Newcastle.

The Baiada poultry building at Beresfield, which had more than 200 people inside, was evacuated.

Ambulance NSW spokeswoman Michelle Hoctor said 26 people were being treated and assessed.

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“Three patients have already been transported to hospital with another ten expected to be transported by road ambulance,” she said.

“We have 11 ambulance vehicles on scene, so yes, it is a major incident.”

Grant Courtney, from the Meatworkers Union, said the situation at the site was hectic.

“Everyone has been marched off the site and no one is allowed to enter the plant because of a major chlorine leak,” he said.