AURORA, ON - Canadian auto parts giant Magna International Inc. is being investigated by the U.S. Justice Department on an antitrust matter in the auto tooling industry.

The company said early Thursday that it was co-operating in the investigation, which centres on tooling contract bids by its Cosma International unit, which produces vehicle body and chassis systems as well as offering vehicle engineering services.

No other details were released.

On the Toronto Stock Exchange, Magna shares were down $1.10 or 2.82 per cent at $37.86 in morning trading Thursday.

"In connection with such investigation, the DOJ has requested documents related to various tooling bids, including a tooling program for which a subsidiary within our Cosma International operating unit acted as Tier 1 tooling supplier," Magna said in a release before stock markets opened.

A Tier 1 supplier is a company that sells directly to an original equipment manufacturer.

"Magna's policy is to comply with all applicable laws, including antitrust and competition laws, and we are fully co-operating with the DOJ," the company said.

Magna is Canada's largest auto parts maker, with 104,000 employees in 26 countries.

The Toronto-area company and its subsidiary manufacture advance systems, assemblies, modules and components, and engineer and assemble complete vehicles.