Armed police are on the scene at Riverlea Wreckers for a pre-planned search.

Armed Police have swooped in on a wreckers yard on the outskirts of Hamilton.

A police spokeswoman said it was a pre-planned search of Riverlea Wreckers and the armed offenders squad were there as a precautionary measure.

A witness told Stuff there was a police helicopter circling the area and that traffic had been diverted away from Riverlea Wreckers.

CHIRSTEL YARDLEY/STUFF Riverlea Wreckers workers sit on the roadside as police conduct a search of the business.

"There's people who seem to be sitting on the ground about 50 metres south of the Wreckers and are surrounded by police."

She said the police operation had caused huge traffic delays as people head in and out of Hamilton on Friday evening.