The Commerce Commission has filed criminal charges against two construction companies and their directors for alleged cartel conduct.

The pair were accused of colluding to rig bids for their publicly-funded infrastructure projects in Auckland.

Commerce Commission Chair, John Small, says their cartels team investigated this historic case right away.

"It's obviously, with a criminal standard, the standard of proof and the standards of evidence, got to be pretty high. Because the consequences are very serious- potential imprisonment- we've got good evidence."

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